It is a valid question. As a 'brand building' advertiser, I never felt like most of the google products delivered as much value as they claimed; they all seemed to be targeted at products people will buy after the first impression (which is... not, generally, how products in my sector are sold. People buy because they have heard of me. The 'hearing about me' is important, not the last click.) and the tracking mechanisms all seemed... naive. (now, that last part might just be the effect of them dumbing it down to the point where a small business owner, like me, can understand whats going on, but man... in that case, we advertisers trust google a lot.)

Of course, I'm small, cynical, stupid, and don't spend much effort on advertising, so it's possible my impression is wrong.