Half-baked Showerthought:
I think the reason places like 4chan or lesswrong are so influential are because to share quality ideas/posts (such as dead internet theory or AI orientation) it HAS to be done outside the platform. People dont have 4chan accounts, you cant just send a post to your friend like an instagram reel. Ideas on platforms like ifunny/instagram/>reddit
stay fairly bound to their platform, if you want to share a post you just send it to someone/somewhere else within that same platform. If you want to share a wild 4chan post you screenshot and send it on/through something else. So by nature it ends up on all sorts of various platforms. And the more it spreads the more people want to capitalize on it, "I should make a YT video essay on this!"
Exceptions: TikTok (it's fucking massive), Discord (ex: "Memes I stole from Discord on YT", but this doesn't really fall under 'influential')
Also, you may find this video interesting:
View: https://youtu.be/2GBs1GapIvw