True and it also enables many smaller sites to function. The big players can adapt to a new revenue model easily, but for a small site maintained by 1-2 peopla

True and it also enables many smaller sites to function. The big players can adapt to a new revenue model easily, but for a small site maintained by 1-2 peopla it's not feasible to have and ad department or start selling ads individually. So aside from its drawback the current automated ad system helps the little guy site owner and any tightening would only result in the small players getting eliminated with the big guys continuing to thrive.