From the article -- "or accept a fair market valuation to be acquired and become a part of something that’s more interesting." The problem is that as a feature it's worthless. It can be recreated relatively simply. It has no value beyond the network effect, and it's been demonstrated a bunch of times that the network effect doesn't follow acquisitions (dodgeball anyone? jaiku ftw?). That is the unsolved problem - not how to build a community, but how to monetize one. I think that facebook (at least until they decided to ripoff twitter) was the closest to solving that problem.