You're confusing apples with oranges, chief. This episode basically said: "Your 10 year old son created a cartoon sensation 12 years ago." (And the episode "I am Furious Yellow aired in 2002, BTW.)
I can understand when people say "It's just a cartoon" to dismiss any critique of surrealism (funny, or otherwise), but this isn't about characters ageing, it's about the writers pushing the credibility of the current humor. Unlike reality, fiction has to make sense.
Also, this guy brings up a great point to the "it's just a cartoon" crowd:
"It's just the way you keep calling it "just a cartoon" as if that means anything can happen because it's just a bunch of random drawings that do not follow any real rules. If characters started flying around in a live-action tv show when it's supposed to be a down to earth show about real people, you wouldn't say "chill, it's just a tv show". Sure, surreal things happened in the classic era, but that's what was established in the show. As long as you were able to accept it, then nothing is wrong, but there is still a line of plausibility somewhere in that universe, no matter if it's animated. Bart skating around the house/yard because of a rope connected to the ceiling fan isn't black-and-white crossing the line. It's subjective, but it was pretty wacky because of the over-convenience and just the way it's executed feels so cheap, whereas Homer falling off a cliff has him in the hospital afterwards or Bart spinning around in season 4 made you feel the momentum of michief and danger. Of course, just because things happened back then doesn't mean they are flawless and that there weren't moments when they were really pushing it. It's a cartoon, yes, and it has more freedom than your ordinary live-action show, but there's still limits."