Well it's not quite so perfect.
Parts of moving instances, like the redirect from the old instance, still rely on the old instance.
And if you're leaving the old instance because of either technical issues or flat out abuse from its administrators, it's hard to rely on that good faith cooperation.
This is just part of the design of Fediverse, unfortunately.
Redirection is part of ActivityPub, though.
If you know of someone existing on a certain instance, you have no choice but to go to that instance to find their new address if they move.
It's a fundamental part of Fediverse, can't be avoided.
No, this is about the people who follow you.
They won't know your new address without the redirect, kind of like needing the postal service to forward your mail to your new house.
Yeah, you export and import the list of people you follow, but it's the people looking for you that become the issue.
What happens behind the scenes is that the instance that you're leaving sends notifications to people who have subscribed to received those notifications.
And if you think about it, it has to be this way, or else I could set up another account and just claim to be you in your new home. The old instance has to be the one to send the notification to prove that it's legit.
