I think you're just noticing the more egregious examples which garner a lot of attention. Quite a lot of original content that didn't have any other common place used to originate on 4chan. Eventually a lot of it shifted to Reddit as Reddit came into being and gained in popularity, but there's a reason that some content (such as very short science fiction stories, or humorous explanations of DND sessions in "greentext") is archived in the form of screen capture images, and that's because one of the few places you could find this with a wide audience was on 4chan.

I've only ever been on 4chan a handful of times, and yes, the boards that people expect to be a clusterfuck are indeed a clusterfuck, but if you pay attention it's hard to discount the influence 4chan had on internet culture in benign ways as well.