"like 4chan" is the godwin's law of social media moderation
Free speech advocates advocating for absolutism in free speech need a counterargument if they're going to go down that road.
In my experience, aggressive moderation, whether by the community or by admins, is the only way to keep a public community from turning into a cesspool, so if you're arguing for no moderation you better have a solution for what that actually entails.
I can give you a counterexample of Reddit that turned into cesspool with (and may be because of) excessive moderation. Just check their front page with posts celebrating people dying of Covid https://www.reddit.com/r/HermanCainAward/
/pol is not the only containment board or issue with 4chan
So like /r/HermanCainAward but without the doxing?
There's plenty of "death of the outgroup" celebration on Reddit even in big subs.
You brought up /r/hermancainaward as an example of Reddit having a cesspool and tried to imply without evidence that moderating it had a hand in its creation, _and_ implied that it’s the same level of cesspool as a place like /b.
Even if we assume you are correct about it being the same level of cesspool, as we speak the Reddit admins have been instructing the hermancainaward moderators to clean up the board or be shut down, which would get rid of said cesspool.
The only thing shown is that people can be terrible as a group, but moderating at least removes the worst excesses. That does not show how to deal with those excesses in an unmoderated forum
You can hold great conversations on any of the like 30 other boards on the site without worrying about censorship or performance for internet points. There is still moderation, just the minimum amount possible.
A default of anonymity also helps curb a lot of spillover into the real world that happens between users of other forum sites.
The only reason 4chan gets dragged through the mud is because its containment facilities (/pol/, /b/, etc.) are among the most active boards. That speaks more to the human condition than 4chan in that people, when given a choice, tend to gravitate towards the least moderated sections of a website because they are the most engaging.
In terms of a solution I think it offers a fairly good one. If you don't want to have to keep banning malcontents across your site, then give them a place to congregate and they will mostly stay there. Try to ban them and they swarm looking for a new home.