Way back in the earliest days of the cypherpunk movement this was one of the things that people thought Chaumian blind signatures were going to offer and one of the crypto techniques that fascinated me the most. These signatures offered a way for a government to issue you an isa-person cert that you could use to sign up for various online services. The thing about this key was that it was like a blinded ecash token, if you double-spent it you could be revealed. If you set up your reddit account with your cert/token then you would get one account, trying to set up a second would trigger a double-spend reveal and your identity would be exposed. You could set up various ways to do blind reveals of specific info (e.g. gender, age, etc) for various types of classification purposes. Stefan Brands pushed this work even further, but it all sort of disappeared during the dot-com bust. Now if you search for 'stefan brands ecash cryptography' google assumes a typo and you get a bunch of links for some shitcoin being pushed by comrade Segal.

A bit of a long and winding road to head off in the direction of noting that some of the old techniques that were being explored in the crypto cambrian explosion of the early 90s are still out there and still have merit. They just seem buried in the back-and-forth jousting between all or nothing when it comes to online identity.