I was going to maybe correct and add a little bit to this recollection by linking a comment I'd made a while back on the subject, but since lemmy can't seem to dig up the post, I guess I'll just kinda summarize.

Sometime a while back, after moot sold off the site, and it got bought out by the japanese dude that runs 2chan (apparently it's also funded by toy company "good smile"), the administrative staff kind of got slowly replaced by a bunch of white supremacists who will selective moderate to kind of create their idealized "free speech" shrouded platform. Mod logs from them got leaked some time ago as evidence of this. I think it's probable that some of those guys are funded by political activist groups in order to do it full time, after 4chan kind of showed it's hand earlier on with the level of efficacy they could achieve with internet hacktivism, but that might be reading too much into things.

I mean, obviously 4chan also needs a large level of moderation, contrary to what people might think. It's historically had some problems keeping up servers, because there would sometimes be CP floating around on the platform at any given time, and whatever company you're renting your servers from, probably doesn't want that shit on their servers. You also need a good filter against extremely large amounts of botposts, or large amounts of corporate spam, as well, which is really the case with any internet community. You can't really survive without some form of content moderation.

It was always kind of less about the new users, then, who can pretty easily be distinguished and mocked/ignored/moderated away (the latter approach is always better), and it's always been more about astroturfing, and who controls the switchboard, who's in the positions of power. "Eternal Summer" is only really a problem when that kind of outstrips the moderation of their ability to properly sift through posts and moderate, at which point, you kind of have some other problems that are more practical, related to scaling up your operation.

User based gatekeeping need not apply, because there's not really much the users can actually do to stem the tide, despite how much users like to squabble over the correct usages and origins of slang terms, surface level distinguishing characteristics, and in-group purity tests. How much people like to bitch about "board culture" and shit like that.

Internet communities are a collage, or a kind of, bacterial culture, that ends up reflecting their moderator's lowest possible standards and sensibilities, I think.

Edit: oh, I should've also mentioned, that in many cases, there's a financial incentive to let new users flood in almost completely unmoderated, because, even if it lowers content quality, it would be better to have lower content quality, but a larger userbase, than do anything that might possibly upset the userbase and drive them away. Oftentimes I think also that high quality content is a demarcation of a userbase that is not easily monetized, compared to low quality content, but that obviously reaches a kind of critical tipping point when the content quality gets so shit that corporate power brokers start to take notice and demand more control.