I suspect the reason that Twitter is cutting off apps from using its “friend finder” feature is because most people do not create content in Twitter and therefore have no incentive to use Twitter outside of the value of its graph. Unlike replicating or using the Facebook graph externally, relocating the Twitter graph can have disastrous consequences for Twitter. Lots of celebrities use Tumblr, and if you can instantly relocate your Twitter graph into Tumblr, then what value does Twitter have, other than different content?
Great theory, and a good piece. It’s fascinating to watch how Twitter is approaching this situation versus Facebook. Businesses and celebrities use Facebook too, but it’s been happy to become a sort of “social OS of the web,” and you can plug your graph in just about anywhere. Twitter locking down its social graph—your social graph—like this seems to be an act of desperation.