A huge point of the article is that valuing search ads like that is highly susceptible to selection bias. My point was that the value of an ad is to displace o

A huge point of the article is that valuing search ads like that is highly susceptible to selection bias. My point was that the value of an ad is to displace other ads, in other words the measurement you look for isn't how many people click through to your site for an oil change but how many do so instead of the next guy.