Earlier quoted context omitted.
That's only true if you choose to introduce a global namespace. There's nothing requiring you to have just a single such catalog of users as long as the canonical reference is the pubkey any more than the contact list on my phone requires you to name people the same on your phone. (and in fact on reading the protocol specs, they do have a way for relays to publish mappings [1] . EDIT: and that would seem to make it p…
Sure, you can have multiple namespaces, and each would have to be censored, but that's about as difficult as playing whack-a-mole with multiple domains pointed at an IP address.
That's fine. But it's entirely independent of whether or not you provide a lookup mechanism for names.