There are some on mastodon that want to live in a fairly defensively disconnected/defederated bubble (compared to many other instances or lemmy/kbin).

And, IMO, that's totally fine and good ... freedom of association gives people and instances that power and it should be embraced when people chose to exercise it TBH, so long as it's done by admins in a way that isn't too autocratic against their users and open and transparent.