"/>I'm reading that , the best known art instance, has, not defederated, but "silenced" because of its lack of moderation and failure to defederate from instancs that mastodon.art wants nothing to do with.
(source - and other recent posts)
This seems to be partly about specific choices the admin Gargron has made, but I think even if he'd made different choices, something like this would be an inevitable consequence of people piling on the biggest instances.
To have a good community you need moderation, which means that the ratio of moderators to people being moderated has to be high enough. If it isn't, the site will become the "Nazi Bar"
You can prevent this by limiting the number of users by some means or another... requiring invites or payment, or just shutting down new registrations.
You can prevent it if you have a lot of cash by hiring an army of PTSD'ed contractors to poorly moderate the horror (the Facebook / Youtube route). This is better than nothing but usually doesn't work that well.
I don't know what other options there are.
The best option for Mastodon would seem to be to divert people into small enough instances that it's an achievable task for the person running the instance to moderate well.
But at this point you may have the problem that there are so many instances that a form of meta-moderation becomes impossible -- the meta-moderation which is "moderating which instances are defederated and which aren't," which is the same kind of work as moderating which posts are allowed and which aren't, except on a grander scale.
I don't know how this is all going to work out. I hope it does.