Every time I rewatch the series I cry like a bitch during the last episode starting from the scene with Kagura and Yukari in the classroom.>>183221276
You really have no idea how big Azumanga Daioh was not just on 4chan culture but on internet culture of the time which is the entire reason it was so influential on early 4chan.
You sound like a kid who's too young to really remember the internet in like 2003 - 2005 (the early days of modern meme shit) but Azumanga Daioh stuff was everywhere, especially anything related to Osaka. Sakaki throwing the snowball, psycho Osaka, Bananaphone, the entire existence of waifu as a term, edited gifs of Osaka kicking off her shoe and probably a few other things I'm forgetting.
Of course it was "popular at the right time" but it's still remembered and its influence is still pretty felt and apparent while other popular stuff that followed it like Lucky Star or Haruhi are largely forgotten or remembered only by oldfags. I think the only thing that's really come close to it in that level of popularity and staying power is maybe K-On. Maybe.