I thought phone numbers were no longer required to use Signal but that would be too good to be true.

You still need them for registering an account and the hash of the phone number still your "public ID" when it comes to the protocol.

The only change is that you can start a new chat by sharing a changeable username and you can hide your phone number from your Signal contacts.

It's still a positive step, but I expected more and now that I know this is what 'signal usernames' amounts to, I'm left disappointed.