Re:Reddit just passed Facebook as #3 most popular website in US
by Retric on Wednesday May 30, 2018 @03:11PM
(#17190719)
Even just targeted advertising is enough. Setup a campaign landing page for each campaign and anyone that clicks the link just exposed their gender or any other criteria you set up when defining the campaign.
(Note, the Cambridge Analytica stuff happened in 2013 when Facebook was much more open with APIs using their data, since popular demand at the time was for FB to be less of a walled garden)