I’m not a big fan of biometrics, which is a solution proposed in the article, though I’ve only read it in part. (I stopped when opposition to biometrics and blockchain was called ideological.) The reason being that biometrics can’t be revoked, as in, once a bad guy has a copy of your fingerprint or whatever, he can forever compromise any system where you authenticate yourself with your fingerprint. Secondly, biometrics aren’t hashable. Biometric values change slightly due to environmental factors, and due to imprecise measurements. This makes it impossible to ever get the exact same measurement again. This in turn means that anybody who runs authentication needs to store whatever biometric is used to authenticate you. Therefore, if they have a data breach, your metrics are forever compromised.