Not that I disagree with what you said, but maybe you can think about it this way (again, contrived oversimplification): - Google are the experts/masters of kn

Not that I disagree with what you said, but maybe you can think about it this way (again, contrived oversimplification): - Google are the experts/masters of knowing "what you want", expressed via your search intents - Facebook are the experts/masters of knowing "who you are" (including demographics, as well as family/friends/connections, interests/hobbies/personality, etc.) Google can guess at the same type of "who" information that Facebook owns (e.g. gender inference), and vice versa Facebook can guess at the type of info that Google owns (e.g. search/purchase intent), but both have distinct relative advantages over the other, which is why there is still competition in this space (the GP comment was questioning, why hasn't Google just "won", why is FB even in the picture, etc.).