I feel like this is the ad-equivalent of the sub-prime mortgage situation, pre-crisis. With mortgages, you had loans that no individual bank or bank manager would want, and then you had an automated process that obfuscated the individual loan details and produced financial products that could be sold as high quality. In the ad world, it's the same thing. You have these websites that nobody would buy ads from, individually, but somehow, through an automatic process offered by Google and friends, the worthless product becomes valuable.