That is a fair point, but . . .

It also brings up the key issue about . . . well, keys. It is frictionless to spin up another keypair. Is is NOT frictionless (in most cases) to get a nip-05 from a respected, established, trusted domain/relay/whatever. Sure, you can just abuse the nip-05 services like the spambots do, but, if you note . . . they all come from the same core domains, which . . . would be handy to have to block domains entirely, and I don't see a good way to do that at a lower level that some clients (very poorly implemented) block/mute lists.