I think the pseudo-elitist dislike against the more mainstream following of a Justin Bieber, Lady Gage or Kim Kardashian will only hurt Twitter alternatives like App.net (ADN). That’s actually why I didn’t really participate on ADN myself until a somewhat more mainstream mass had started using it: I don’t like intellectual bubbles.
Silicon Valley/SF has long become exactly the kind of pseudo-intellectual bubble that over-prides itself in things and fails to have the self-awareness needed to communicate effectively and add value to the real world out there. ADN should not become the online equivalent, so IMO, bring on the Biebers! And also: let's stop looking down on their followers. It helps no one, ever.