The whole online identity thing was a solved problem well before that. You sign up for a service, you give them your email address and create a password, now they know who you are because you have your password, and if you forget your password they send a reset code to your email. Add 2FA as you like.

That allows you to authenticate with the service you're doing business with, which is all that ever needs to happen because centralized identity systems are just an attack for correlating your activity across services and devices.