Last night, The Simpsons celebrated its 500^th episode with “At Long Last Leave,” an examination of the view the rest of Springfield has of its most famous residents. With such an explicit “why do we stick around these people?” plot and such a big milestone, it’s an interesting time to look at what The Simpsons means, how its cultural role has changed over time and why that’s not necessarily a bad thing.

It’s no surprise that after 23 seasons with 500 episodes, people have some Strong Opinions about The Simpsons and how it’s changed over time. The most common one you might hear is that the show isn’t what it once was, that after being on the air so long, it’s lost a lot of the verve it once had. This is often followed by a discussion of when the show’s real prime was, and it varies from person to person. Some people prefer the original Mike Groening, James L. Brooks and Sam Simon episodes that made up the first two seasons or the two Al Jean and Mike Reiss seasons that followed it. It goes on. Different years’ showrunners are remembered with different levels of fondness by different people. I know the episodes that I’d place among my favourites – “Marge vs. the Monorail,” “Deep Space Homer,” “Homer at the Bat” and “Citizen Kang,” the last segment of “Treehouse of Horror VII” where aliens infiltrate the 1996 US presidential election – and chances are, they’re different from the ones you’d select. That’s part of the beauty of a show with so much of itself as The Simpsons: there’s something for most everyone. I have a particular soft spot for the first seasons I watched, the ones I grew up with. I absolutely agree that compared to those episodes and seasons I have such an unbreakable bond with, the later seasons don’t compare as favourably. Nostalgia is a hard thing to one-up.

Of course, another reason the show might not seem as rewarding as it used to is because whereas in the beginning it was truly iconoclastic and breaking ground for what an animated show could be, at some point in 500 episodes, what used to be innovative instead became par for the course. How many times can an episode be about the Simpsons going somewhere or meeting someone? How many unique plots are there in Homer being stupid or Lisa feeling out of place in her family? Probably not 500 episodes worth.

This isn’t The Simpsons’ fault. What would the show’s crime be, if it were? Being too successful? That’s hardly something to fault the show for. Sticking around too long? That’s something else entirely. It would be a compelling argument if the show wasn’t accomplishing what it was meant to anymore, and if the metric to judge it by was innovation, I think there would certainly be a very good argument to let the show trod off into the sunset. Here’s where that argument loses ground, though:

The Simpsons isn’t about breaking ground anymore, and that’s okay.

The biggest part of this is just simple math. After a certain number of episodes, it’s hard for a show to surprise anyone, especially in a show without a rigid continuity, where the characters have been the same age for over two decades. With a soft reset button at the end of most every episode, there’s a limited number of stories you can tell before a lot of it ends up rehashing. “That ‘90s Show,” the eleventh episode of the nineteenth season was a pretty big example of this because it was arguably the first – and to this day, biggest - major instance of the show lapping itself and overwriting whatever loose canon there was in the first place. With “That ‘90s Show,” The Simpsons removed the events of the classic episode “Homer’s Barbershop Quartet” from the characters’ history. Instead of starting The Bee Sharps in the 80s and meeting George Harrison, he invented grunge and drank Zima. Some have and will find that crass, but really, it’s just a signifier that there’s only so much room for “new” things. After a while, you just have to stop or clear out some memory.

When the show began, of course, everything was new. The idea of an adult cartoon was almost unheard of. The Flintstones was the first major animated sitcom in primetime, and broke a lot of ground, but it was decidedly and wonderfully directed at the entire family. But The Simpsons? It was directed at adults. It featured a juxtaposition of crude humour and highbrow references written by Ivy League graduates and it was the first major hit for the Fox network. As entrenched as it is now, there was a time in the relatively recent past when Fox was a young upstart, and one of the biggest reasons it’s a major player now is because of The Simpsons. In 1997, the show passed The Flintstones as the longest-running animated US sitcom on television. In 2004, it became the longest running US sitcom and 5 years later became the longest running scripted primetime show in the country’s history. Its highest rated episode drew over 33 million people (despite still being the week’s eighth most popular show), which, for some perspective, is twice what the highest-rated television show, period, got last week. Despite starting as a rebel, it became incredibly successful and at one point, it became the establishment.

This isn’t a bad thing. Rebellion is for the young, and the show stopped even pretending it was trying to be that kind of show over a decade ago. It settled for massive, unprecedented longevity and success, which is hardly settling at all. Instead of breaking ground, it became something else: an old friend.

The Simpsons stopped consistently surprising anyone quite some time ago, but what was left was either something you let go as you moved on, or a familiar companion that you check in on. I’ve been watching this family for almost 20 years, ever since I was old enough to sneak episodes whenever I could make sure that my parents, who forbade the show in the house, wouldn’t catch me. I’ve known the family as long as I’ve known any of my friends, and that’s what they’ve become. It’s fun to watch the old episodes, the ones that almost anyone my age has burned into a brain and can quote on demand. It’s also fun to watch new episodes. They might not be as brilliant as the old ones, and they might not break any ground, but I laugh and feel good that the characters are still out there. Sometimes, it still shows flashes of that old genius, but the rest of the time it’s still The Simpsons. It’s a show I grew up with, and over the years I have gotten different things out of the episodes as I matured and changed. The show’s role has changed over time, and that’s okay.

It’s more than okay, actually: it’s expected. If no show can be iconoclastic forever, than it has to change to fill a different role. As it becomes the old friend, new ones step in. The Simpsons changed the face of television, not just in terms of adult animated programs, but in terms of the kind of jokes you could tell and what you could get away with. Still, it could only enact so much change and still be the same show, so when it got as far as it could push, it was time for something else to step in. When Family Guy began, it was a shock to audiences. It got to the line The Simpsons couldn’t cross and bounded over it. It enflamed and offended people, died, changed television, and then came back to life.

Of course, just like its forbearer, it could only go so long without before it became a known quantity, its ability to shock the masses subsided and it became part of the establishment. Don’t think it’s part of that same circle as The Simpsons? It’s been around for 10 seasons and even more years. Merchandise with the show’s characters and slogans on it has gone from being sold in Spencer’s Gifts to being on aisle ends at Walmart. It’s gotten a related show (American Dad) and a spin-off (The Cleveland Show), crossed over with Bones and now its creator is going to relaunch The Flintstones. It’s gotten old enough that, like The Simpsons, it’s become a familiar friend. This is the life cycle of groundbreaking television. At some point, it stops being able to give an audience bold transgression and something takes over. This cycle keeps on going.

So if The Simpsons begat Family Guy, what comes after the latter? It’s hard to think that anything could push any more buttons than that show and still air on a network, and that’s absolutely correct: network TV is about as far as it’s going to go anytime soon regarding standards and practices. The next Simpsons or Family Guy won’t be found on network television, but on cable. It’s an environment that can give audiences something like South Park, another post-Simpsons product, for 15 seasons without having to worry about big audiences or pleasing affiliates. Ratings that would be instant death on Fox mean cable success, so a show can scare away or offend a large amount of people and still keep going. South Park couldn’t air on network TV, but it’s lasted a decade and a half on cable; a long enough time to also push all the boundaries it can. But cable still gives us shows like The Venture Bros. or Archer, which can surprise and shock us without having to worry about too many of those consequences. A cable television show will never be as culturally pervasive as network TV, and in this era of niche audiences the numbers will never match that 33 million The Simpsons got when it ran against The Cosby Show, but that’s where the new directions are.

The Simpsons was an iconoclastic show that changed television. It was so successful that when it finally got a feature film, there were real-world versions of its fictional stores and products to promote it. That’s about as big as a television show can be, but that success and ubiquity comes with a price: when everybody knows you, they can know what to expect. When The Simpsons stopped innovating, other shows took over, and even more shows will take over for them. Media will keep changing the world, and in the meantime, we still have our old friends at 742 Evergreen Terrace and the stories they’ll still tell us if we sit down and listen. That’s pretty amazing, and I’m not ready to say goodbye to them any time soon.