Comment by Thorrez

It might be the case that the designers of email and the designers of ATProto and the designers of AP all assumed the owner never changes. But I think the actual behavior of the protocols in the event of a change is different.

For email, if the owner changes, the new owner gets full control. This is nice for the new owner, but maybe not so for the old owner, because now any emails meant for the old owner can be read by the new owner.

For ATProto and AP, it sounds like in the event of an owner change, things kind of break. This protects the security of the old owner to some degree, but means the new owner can't really do much.