alt Hacker NewsGoogle's real advertising proposition is they will sell you the audience of an expensive website on a cheaper website. Want to advertise on the New York Times? Why pay their high rates? Google tracks who visits the NYT and offers the advertiser the same audience when they visit Bob's hobby gardening website, which is considerably cheaper to advertise on. That's really why they want to track where you go. Understanding what you want is just a secondary aim to that, if they are interested in it at all, and I agree with the article that they are very poor indeed at it.
Hard to imagine all the combined various bob spend is really very cheaper than a single better placement. You have to imagine this also puts downward pressure on those nyt placement prices and upward pressure on bobs.