Re: let the publisher decide which ads they want to display?
They used to, but it's considerably easier for display marketers to set up ads on Google, throw in some targeting criteria and let the algorithms work it out.
It lacks the craftmanship of the old days where you would specifically choose which sites your ad would go on based upon supposed interests of whoever is likely to see that page.
There are other advantages like how Google only attributes an impression after the user actually sees 50% (iirc) of the ad rather than just loading a tracking pixel on page load and saying that the ad got an impression even if the user never saw it. Another advantage is that while you don't hand pick where you want the ads to appear, you can do a whole hell of a lot more volume with one person managing a GDN account than keeping relationships up with a host of individual content publishers.
Biting the hand that feeds IT
