Edit: But missing a key issue, perhaps.
> Because Mastodon uses a collection of Instances, you’re not at the beck and call of one site owner. If you don’t like the direction an Instance is taking, you can pack your virtual bags and go. Mastodon even has an import/export tool that allows you to migrate the people you follow from one account/instance to another.
That sounds great. But if you do "pack your virtual bags and go", is there any way to map foo@bar.net to foo@baz.net? In the email analogy, there's clearly not. You need to tell all correspondents.