A key part of federating, at least notionally, is ease of migration. The local pub locks their customers because there’s no alternative. Twitter locks their users because their “followers” aren’t on the new platform.

The fediverse facilitates migration, all the way down to redirecting from the previous account. Doesn’t look like there’s a way to automatically update followers’ following, and there probably shouldn’t be, but follower count (including all of the inactive and bot accounts) is one of the tools commercial social media use to scare people into staying.