By the end of 2010, Facebook's dominance of the social networking landscape had moved from impressive to structurally overwhelming. The platform had crossed 500 million users in July, was adding new members at a rate that no competitor could match, and had become — for large portions of the global population — the default answer to the question of how to stay connected with friends and family online.

MySpace, which had once been the reference point for social networking, had been in functional free-fall since 2008 and would be sold by News Corporation in 2011 at a fraction of its purchase price. Friendster, the original template, had essentially been relegated to Southeast Asia. LinkedIn maintained its position as a professional networking category, distinct enough from Facebook's social focus to coexist rather than compete directly.

What made Facebook's dominance distinctive was the network effect in its most powerful form: the value of being on Facebook was directly proportional to the number of people you knew who were also on Facebook. By 2010, for hundreds of millions of users, the answer to "is everyone I know on Facebook?" was yes — which made leaving or switching not a consumer preference but a genuine social cost.

The David Fincher film The Social Network, released in October 2010, arrived at the perfect cultural moment — telling a story of origin and betrayal that audiences already cared about because they were living inside the product the story described. The film's portrait of Mark Zuckerberg was contested by its subject but undeniably compelling.

What Facebook would do with its dominance — for users, for advertisers, for democracy — remained, at the end of 2010, substantially undetermined.