Yes. And isn't it also the case that, by offering their very elaborate targeting capabilities to advertisers, they still leak your personal data to 3rd parties, though indirectly? After all, the fact that a certain personalized ad appears in your page confirms to the advertiser that you are in their carefully crafted target group.
(I work for Google, but not on ads and I have no social knowledge)
I think that one thing Google tries to do is to make identifyingly small demographics not possible. As you say, that would leak personal info when the user clicked.
