I won't speculate, but I'll throw it out there that a lot of people don't even realize it's Judd Apatow who's responsible for 90% of their favorite comedy. I mean, it's understandable, right? After all, he's not actually IN the movies themselves and therefore not relevant to the movie's success.
Writing, directing and producing isn't what makes Hollywood go 'round! It's the talent!! I wish you all could see me hard rolling my eyes right now.
In all seriousness though, I do get it. I didn't realize for a long time myself. I just kept watching all of the movies below time and time again (seriously, I know EVERY word to about 3/4 of them) wondering why they all felt so similar. It couldn't have just been a coincidence, right? Right! I was onto a trend, or pattern if you will.
They all felt so iconically hysterically because Judd Apatow has his hand in each and every one. He didn't necessarily write all of the films on this list, but he does have a credit by way of directing, producing, or writing and in my humble opinion that's the bread and butter of any good movie.