"Heck, web ads give the user an instant way to click through and act on the ad" And that is the problem. Because the ads in print just sit there, the only way

"Heck, web ads give the user an instant way to click through and act on the ad" And that is the problem. Because the ads in print just sit there, the only way to measure the effectiveness is in increase in sales. On the web however, the sales are web sales and the advertiser forgets completely that a customer might have seen the ad and decided to go to the shop instead. So it's advantage is its downfall aswell since it constrains the metric used to measure hence undervaluing the effectiveness of web advertising.