One day startups will learn to stop building on negative/zero/low revenue social networks. After hearing about Zynga getting diversified almost out of existence on Facebook, Dalton Caldwell being served with a "Join us or else"[1] from Facebook, and the Twitter 3rd party castration[2]; it amazes Me that people are still trying to build services on top of social platforms. These platforms are generating very little revenue relative to their valuations. If you have this amazing service that starts making money or getting notoriety, it's in the social networks best interest to stop your business and build the feature themselves.
While I agree with you in general, Klout actually launched Cinch themselves. It was supposed to increase the usefulness of their network to their users.
[1] - http://daltoncaldwell.com/dear-mark-zuckerberg
[2] - https://blog.twitter.com/2012/changes-coming-to-twitter-api