The problem is there are many smaller publishers on the net where a handful or only one or two people maintain a site. They don't have the capacity to look for

The problem is there are many smaller publishers on the net where a handful or only one or two people maintain a site. They don't have the capacity to look for advertisers or vet individual ads. That's why they use an ad provider which does this for them. What you say may work for big news portals and stuff, but if this becomes the norm then it will kill the small publishers resulting in further concentration of net content in the hands of the big guys. So this direction would hurt the little guys and help the big guys, because they have the resources to adapt.