Because it won't take off. Right now, the advertisers are basically hoping for you to be too lazy to click around ten minutes to find the 'no'-option. If every

Because it won't take off. Right now, the advertisers are basically hoping for you to be too lazy to click around ten minutes to find the 'no'-option. If every user would be presented with a fairly weighted chance once, hardly anyone would click yes. Accepting this standard would undermine their business even more.