Social networks pose a really interesting problem to the usual capitalist model, where competition (y'know, theoretically) ensures the best outcomes for consumers over the long run. If you build a definitely better automobile than General Motors, even only slightly, you can compete and bring the price down/quality of life up for the customer. If you build a definitively better social network than Facebook... no one cares. They're only on Facebook because their friends are. You need to vastly exceed their experience before they'd even consider it.

When the normal checks of a single business dominating a field fail, we need to find new solutions, especially when that field is communication. We don't want a future in which Facebook is non-democratic, but everyone gets their media from it and can't see a good reason to leave. I would hope that over the long term, we figure out public ownership of social media, and enshrine control and understanding of the systems that bring you information as an important right.