Email addresses have worked pretty well, and have the big advantage of allowing "self-custody" via using your own TLD, but don't require it. I don't have any i

Email addresses have worked pretty well, and have the big advantage of allowing "self-custody" via using your own TLD, but don't require it. I don't have any issues with also allowing phone numbers as identifiers and most people preferring these, but I don't want to be forced to do so myself.