I'm not sure that the "need" you're talking about is a practical one, though. Maybe it's an ideological "need", at best. More than enough people and websites seem to be getting by just fine without using Persona.

I think if there truly was a pressing need for Persona, we would have seen it get adopted rapidly and quickly. That's exactly what happened with Firefox. That's also what happened with Thunderbird, although to a lesser extent.

Openness is ideal, but it also requires some demand for that openness. Open systems that aren't adopted are really quite useless.