Were this to become popular practice, surely: (1) Overall advertising industry spend would remain constant. CPC would go down. Distribution of advertising reve

Were this to become popular practice, surely: (1) Overall advertising industry spend would remain constant. CPC would go down. Distribution of advertising revenue may shift slightly towards sites with more "savvy" users. (2) If, miraculously, distribution shifted significantly, advertisers would view this as damage and work to route around it.