In addition to what the other user said, usernames are both optional and easy to change in order to prevent spammers from finding you. Plus, they can only make so many accounts themselves, with the phone number limitation in tow.
https://signal.org/
In addition to what the other user said, usernames are both optional and easy to change in order to prevent spammers from finding you. Plus, they can only make so many accounts themselves, with the phone number limitation in tow.