Just because Facebook doesn't offer finer-grained data points to advertisers doesn't mean they don't collect & use them internally. Given their business model, not doing so would be stupid.

I believe they still have a feature called "lookalike audiences" where you can target a certain audience and let FB bring you more of "those" people - "those" being defined by an opaque algorithm fed way more data points that advertisers and even the users themselves are aware of.