Comment by danpalmer

No it wouldn't, because each Mastodon server can choose who to federate with and many servers don't federate openly or don't federate with smaller hosts for technical, scaling, or even political reasons.

I've done it, self hosted Mastodon limited my ability to participate in the social network in a way that it does not on ATProto.

Also you can't port between instances. Whereas this is fundamental to the ATProto ecosystem.