Then we require a phone number for everything (it's not easy to make unlimited new phone numbers) and use OIDC to authenticate to one of a couple providers. You won't be able to do anything on the internet without logging in first, but the login is safe at the identity provider.
If you think about it this is no different than showing your ID to get into a bar.
If you think about it this is no different than showing your ID to get into a bar.