Social networking is a precondition for new modes of information exchange, not an end in and of itself.
By definition, a social network is simply a set of connections between different people represented by a computer system. These representations wouldn't provide value to anyone if they didn't enable the exchange of information in novel ways. When you friend someone on Facebook, connect with them on LinkedIn, or follow them on Twitter, you aren't doing it for academic purposes; you're doing it to communicate. You don't care about the improved integrity of the social network; you care about the ways in which you can use it to interact with people you care about.
These networks share important characteristics with one another but crucially differ in even more important ones. The differences are more important, if also more poorly understood, because they allow each of them to present unique ways of exchanging information. If that weren't the case, society wouldn't need more than one social network.
There are three categories into which these differences can be broken down to better understand market demand for various social networks. First, there is the question of relationship, or the significance of the people forging connections to each other on a given network. Second, there's the question of content, or the type of information that can be shared across the network. And third, there's the question of mechanism, or how that information can be published or consumed, which affects not only its production and distribution but its meaning as well.
These categories form three pillars of effective social networks. Weaknesses can and inevitably will be tolerated within any given pillar, but each must be strong overall or the network won't constitute a compelling way to exchange information. Additionally, new social networks must differentiate themselves from existing ones by establishing at least one (but not necessarily all) of these pillars differently, thereby giving people a reason to adopt another network.