Is that what FB does? Or do they just use their data internally to target ads, without handing the data to the advertisers? I honestly don't know but I do know that people are always saying that Google sells your information to advertisers, and they don't. So I'm skeptical of this claim.

Anyway, maybe this whole analysis was based on public profile data.

In this case, I don't think the distinction is really that important; I think checking if someone is single or in a relationship to target them with an ad is more intrusive than checking if they're in a group of a few dozen thousand people who are single and like cats.

If either of these companies actually sold the data they've collected they'd hurt their own competitive advantage.