But you have to remember a million passwords, or have a password manager remember them for you. (You don't just use the same password everywhere, right?) You co

But you have to remember a million passwords, or have a password manager remember them for you. (You don't just use the same password everywhere, right?) You could do the same with user names. Sites that use your email address as a login credential and also display your username to the public already separate the two, so there's no additional complexity there.