I know they exposed identifiers in friends lists as well, long into 2013 as I recall. I remember hanging out with friends and grabbing the Inspect Source HTML from their little "Friends tile" that had a ranked list of Identifiers that were based off of how much their algorithm thought we were friends. It would display a random selection from the top 50 or so but all 50 were in there and were fairly accurate as to who I interacted with most on Facebook. My friends and I would log them all then compare notes.

I never had any illusions that Facebook wasn't spying on me: I just had illusions that they wouldn't be so stupid as to sell the only thing that makes them valuable in a raw format to customers.

Google at least just sells you targets.