Craigslist’s generic market place gave rise to fifty or more single-purpose alternatives some of which are quite valuable companies: AirBnB, Care.com, 99Designs, oDesk, CustomMade, Gazelle. Each of these startups operates verticalized market places that solve customer problems better than Craigslist’s generic platform. In so doing, these startups have grown their observed markets. The same unbundling trend will happen to social networks. Generic social networks will continue to succeed. But their most attractive users in the best segments will be systematically poached by verticalized competition.