To me, Persona never _shipped_.  They still discourage self-hosting the identity verification code, so even on a happy path where the user somehow managed to get an email provider that natively supported Persona you still had to talk to Mozilla servers.  That&#x27;s not federated identity, it&#x27;s centralized; it offers nothing above Facebook Connect.<p>Would doing that alone have made Persona a success?  Probably not.  But as it is, it&#x27;s not even in the running.<p>(Context: I wrote my own IdP, so in theory I could have been on that happy path.)