I was using it for years on our sites, IT IS very easy to implement for a developer, especially easier than dealing with oauth oddities from google,facebook,microsoft etc<p>Yes one can program own username&#x2F;password etc login, but it is actually alot of work making a proper one with all the edge cases (, password strenght, email validation, verification, account recovery) and so on and so on. I know because I have done it dozens of time and each time the project has slightly different requirements<p>Mozilla Persona was dead easy to implement on the other hand! Also alot of people did not like and complained about having to login with Google, Facebook etc yet the same people had no issues trusting Mozilla due to the goodwill they built up with firefox and their fight for privacy