Is it not possible to create a social network where the product is the social network? Perhaps not. App.net attempted this, and wasn't able to generate enough money to both keep the lights on and pay its employees.
As someone who once founded a company that published game books, I'm acutely aware of the fact that people are rarely willing to buy content in this age of free information. So what, then, would make them willing to pay to be a part of a social network?