Comment by chatmasta

The point of forcing ads onto users who don't want to see them and won't buy anything from them, is that the advertisers will still pay Google. In the long run, their CTR will suffer, but it will be consistent across advertisers. If they're paying per click then nobody loses except the user, who Google is betting actually will click on some ads (meaning they're basically engaging in psychological warfare, or at least rewarding the advertisers who do). And if they're paying per impression, then advertisers will see conversions go down in the long run, but Google might think the increased volume will make up for it.