That's unfortunate to hear. I would have hoped that you'd be more aware of its actual level of adoption.
Taking an objective look at the situation, as somebody who isn't tied to the project, I just don't see it being used. While so many web sites and applications allow authentication using Google, Facebook, Twitter and even some other more obscure providers, I never see Persona listed as an option.
The adopters listed in the article are minor, at best. Given that the BrowserID initiative has been public for almost two years now, it's not a very impressive list.
It's easy to write blog articles claiming that "hundreds of millions of Web users are now ready to log in with just a few clicks", but we just don't seem to be seeing that actually happening in practice.
I contest that GNU Mailman, the Eclipse Foundation, Firebase, the Born This Way Foundation, and Discourse are hardly "minor, at best." Not to mention extensive dogfooding within Mozilla itself.
Less flippantly, these things take time. While the initiative has been public for some time, it's only been in beta for roughly 6 months. It would be irresponsible for many organizations to jump on board this early, and taking that as a sign of failure is disingenuous.
This is news to the Persona team.