Ironically, this is only possible because advertise resellers created all sort of markets for scamming the publishers of actually getting paid for the ad they show (advertises have to pay for 3rd party reporting, brand protection, etc, etc, etc. all that dillutes the $3~4 cpc the brands pay to the 3c the publishers receivers in the end)

if it worked like it works in TV or radio, this wouldn't be possible to begin with. or wouldn't be profitable.