Man, those fucking assholes. How dare they make us scroll and use up less than a second of our time!
For one, it's not "less than a second" because it often takes several seconds simply to download these huge full-page animated banners over a mobile connection. And the fact that mobile sites are several MB's large now means you use up your tiny monthly data cap quickly. Then as you're trying to scroll past (or more often tap-to-dismiss an ad) it gets accidentally pressed and you have to close a new window. When you have to do this for every page it gets tedious quickly.
It's a horrible user experience that shouldn't be defended.