With google I do a search and get result. In other words there is a feedback mechanism that provides me with opportunities right there and I want the result (thats why I am searching)
FaceBook does not have this mechanism. Instead they have to find gaps where they can communicate to me. However, I might not be interested in any answers/suggestions at that time.
That I "like" StarBuck does not mean I like mcDonalds btw and it does not by any metrics mean that I want any of them at the time I read the ad.
So I don't believe they can predict and I know they can't serve the "suggestion" when I need it.
Google does not even need to know what I am intersted in. I can one day decide to get something completely out of left field and it can serve me answers based on that.
Facebook is still just interest based advertising it's not intent based.