Basic username and password auth has worked for millions for decades.
If you absolutely must collect user data for some reason, an email address can be used as the username. This isn't a hard problem to solve.
For us it had nothing to do with collecting user data, adding what you mentioned would have just required another few hours of dev time haha. You’re right that it’s not hard to solve, we just wanted to focus on the rest of the app since there’s only two of us. We can definitely add this though!