wrt GP: "generating just enough content for the site to make the user visit and show them ads" is how publishing has always worked, even way back when it all came on dead trees. My library had a book in the reference section that had, for various types of demographic, the maximal percentage of ads to run (ie, how much content you needed to pay for having sold a given volume of ads), but it would probably have been almost as quick, just as cheap, and likely more accurate, to empirically determine that percentage by visiting a local newsstand and sampling the ad density from your target section of the rack.

wrt Exit vs Voice: https://news.ycombinator.com/item?id=46376098