It really doesn't look all that easy. https://developer.mozilla.org/en-US/Persona/Quick_Setup
Especially compared with usernames and password, which is basically built in to anything already.
Especially compared with usernames and password, which is basically built in to anything already.
I think that usernames and passwords are "easy" is something of a sunk cost fallacy, both for developers and users, and we tend to forget how much time and effort we "waste" on this year over year. My password manager is up to hundreds of different passwords I use, and I know a lot of users these days whose "password" starts with the now ubiquitous "Forgot Password" button (which is its own headache to setup and get right), as they are okay relying on the relative security of their email address over the fragility of their own memory.