[krupan]

Identifying yourself is the whole point of logging in to a website. Yes, if you want to maintain a distinct digital identity for each website you’ll need to use a different key pair for each website, which by the way is actually feasible.

With our current email-address-and-password scheme that is so difficult to do it might as well be impossible. You’d need a distinct email account for each distinct digital identity that you want to maintain.

[GoblinSlayer]

If a web site wants your email address or phone number, it will require them, asymmetric cryptography won't help you. On the other hand, this very site uses password authentication, but doesn't require an email address.