Comment Mark Zuckerberg recently endured a grilling from the US Congress over Facebook's inability to stop bleeding user data. A week later, investors rewarded his company with a $50bn increase in its market capitalisation on news that – surprise! – a massive userbase pays big dividends.
But it's worse than 87 million users' data that was "improperly obtained" from Facebook by GSR, part of which was later licensed by Cambridge Analytica.
Sure, Cambridge Analytica got the headlines, but there's a less reported side to Facebook data sharing. That is, when companies – retailers, travel sites, banks, media and a plethora of apps – invite you to take the oh-so-simple and hassle-free step of logging into their application or service using your Facebook credentials.
Convenience for a price
Of course, the reason we use things like Facebook Login is convenience, both for the site developer and the end user. Rather than create a user name and password for every random website, developers can simply piggyback on Facebook's (or Google's) generosity.
For its part, Facebook will happily tell you why it's a great idea for developers. Take Skyscanner, for example: "Using Facebook's Analytics for Apps cohort analysis, the team improved their onboarding messages for new launches based on the 'first launch to search' patterns of their cohorts, thus increasing Facebook logins by 2X."