https://qz.com/1083825/facebook-on-russian-ads-our-platform-doesnt-influence-people-people-influence-people/

When fake news found a massive audience on Facebook during the run up to the 2016 US presidential election, it was aided by Facebook’s algorithms that surface stories on topics users are interested in. When a Russian group with ties to the Kremlin used Facebook to launch an ad campaign aimed at influencing American voters, it wasn’t subverting the functionality of Facebook’s ad system, but using it as intended. And when ProPublica discovered that advertisers on the platform could target people who identify as “Jew haters,” it wasn’t unearthing a bug, but confirming the cold precision of a well-working feature.

“We never intended or anticipated this functionality being used this way—and that is on us,” Facebook COO Sheryl Sandberg wrote a post on Sep. 20, referring to the ad-targeting issue. “And we did not find it ourselves—and that is also on us.”