SAN FRANCISCO — Facebook last week suspended the Trump campaign’s data consultant, Cambridge Analytica, for scraping the data of potentially millions of users without their consent. But thousands of other developers, including the makers of games such as FarmVille and the dating app Tinder, as well as political consultants from President Barack Obama’s 2012 presidential campaign, also siphoned huge amounts of data about users and their friends, developing deep understandings of people’s relationships and preferences.
Cambridge Analytica — unlike other firms that access Facebook’s user data — broke Facebook’s rules by obtaining the data under the pretense of academic use. But experts familiar with Facebook’s systems and policies say that the greater problem was that the rules for accessing the social network’s information trove were so loose in the first place.
Facebook chief executive Mark Zuckerberg in 2007 invited outside developers to build their businesses off Facebook’s data, giving them ready access to the friend lists, “likes” and affinities that connect millions of Facebook users. Practically any engineer who could persuade a Facebook user to download an app or to sign into a website using Facebook’s popular “log-in through Facebook” feature would have been able to access not only the profile, behavior and location of that Facebook user but also that of all the user’s Facebook friends, developers said.
