They are free to have whatever kind of vibe they want, but yeah their rights should end where mine begin and all of that. Except they don’t, as even outside of their local communities they constantly violate the rules of other spaces, then their admins refuse to police them, even going so far as to be caught lying to the admins of other instances.

At that point, defederation remains the only available option, except even that is not the end of the matter when so many instances choose not to do that. Leaving the vast majority of the moderation burden to be placed upon the end user causes people to flee the Threadiverse like the 4chan-style place that we legitimately are.