What does that mean? When you post, who’s server’s outbox do you post from? Inboxes and outboxes by server are a central part of the standard.
You can copy over a user, and make another similar account (like pixelfed), or you can do stuff on that server from another federated server, but at the end of the day you’re not on the same account on different servers.
Unless you changed activitypub, right?
Sure. It’d be a pretty huge departure, though. To a weird degree, like Coca Cola leaving the beverage business becoming a tire company.
If you wanted to make a new protocol, you could go beyond federation and have a fully decentralised system where everything happens on arbitrarily many servers in parallel, but that would be a lot of work and probably data-heavy before any users walk through the door.