TL;DR dont throw out the ad networks with the bad advertisers. Its often a precursor to a better solution for everyone involved. All you really need to know is

TL;DR dont throw out the ad networks with the bad advertisers. Its often a precursor to a better solution for everyone involved. All you really need to know is that when ad networks work, the first people to exploit are bad actors taking advantage of little competition. The networks need these guys to survive, so they tolerate it until they can afford to kick them out. As the network matures, it kicks out the bad actors amd it becomes a healthy and effective medium for brands to communicate with consumers in a win-win-win way.