The point is that there's no single point of failure, no centralized control, and your emails are guaranteed to sit encrypted at rest. Seems pretty cool to me. If it becomes production ready, I could potentially switch from Proton. You're right that using an npub for it is a bad idea though. You could implement it with a username/password too. There might be some multi-hash encryption algo that allows you to have a recovery key to change your password.