Anyone who wants to see a demo of it, just sign-in here (top right):
https://login.persona.org/Anyone who wants to see how easy it is to deploy (JS on your page, a button, and callback verifier on your server): https://developer.mozilla.org/en-US/Persona/Quick_Setup
Anyone who wants to see it in action: https://www.lfgss.com/
I love everything about Persona except for the fact that Mozilla are no longer supporting a team around it, and it was given to the community in almost an abandon-ware fashion.
The idea that this could have made an impact faster is laughable, choosing an auth provider is such a slow process requiring considerable points of trust to reinforce it... one of the most significant points of trust was Mozilla itself, but it also needed a social reinforcement as more people adopted it. Mozilla didn't give Persona the time it needed.
My criticisms of Persona are nothing to do with the fungible nature of email as identity, which I think is OK enough in principle (it's no less identifying than anything else and changes less frequently than a phone number), but to do with:
1) The way Persona wants to centrally log-out from all sites, when a user's experience is that they can sign-out from one site and remain signed-in on another.
2) The lack of 2FA in the default instance they shipped/supported.
3) Some of the phrasing and language confuses users, especially after changing to Persona. i.e. They were still a user on my site identified by email address, but Persona would declare that they were not recognised... so I'd have to spend time telling the user to ignore that and sign-in anyway.
The core product though, was exactly what the web needed, and exactly what I needed for all of the sites I run.