I haven't used Mastodon, but my experience with Lemmy was a lot of petty fighting about who should be defederated. The OP's reference to warring fiefdoms was very spot-on for that scene. I imagine it's a huge turn off to casual, well-adjusted people exploring the space. But I wouldn't know.

There's, of course, another sort of grossness to corporate moderation from above, but at least with ATProto you can take your identity and content to another AppView, if it wasn't shown there already. AFAIK, any fediverse migration tooling requires a cooperative host server you haven't already been banned from.