No one is stopping you to migrate from an authoritarian country either (most of the time) and yet they’re called authoritarian. Also, I’m not saying instances “shouldn’t be allowed to defederate”, I’m saying advocating for this on a general instance with 100K users is wrong. If this was a niche or small community with agreed upon and shared values (like beehaw for example) that would be understandable.
Saying things like “Oh, But You Can Run Your Instance” is dismissive of the issue, There’s literally no option to migrate accounts and expecting average users to deal with this mess is beyond me.