Right. I like mastodon's approach to moderation and ownership, it makes sense. But it's wrong to think of it as some sort of 8chan anarchy.
8chan wasn't anarchy. It's a closed fiefdom that had a highly permissive moderation policy. It could have decided to change at any time, and there's evidence that the owners manipulated it as well such as pretending to be "Q" and modifying trip codes for certain people.
Whomever admins the system owns the system. True for any Mastodon instance and true for Twitter.