This is the worst of all possible market definitions. That the market is the thing which only this company does. Most of the companies are choosing google (or f

This is the worst of all possible market definitions. That the market is the thing which only this company does. Most of the companies are choosing google (or forced to choose google) because of the reach and the traffic it gets you. They are free not to spend on Google, use Facebook, Amazon, or any other network (many exist but people arent so aware), the returns are very very low. Its a moat for Google given that their targeted marketing is very very accurate compared to other networks. Same goes with Facebook. If you limit them, you are not improving your ROAS or even efficiency. For most of the companies, they would end up spending higher per qualified lead compared to what they get from Google. This is very hard to break and side by side ensure that the advertisers (and publishers) are not harmed in the process. Facebook has its own audience Network, but that is really bad in terms of returns. There are others like Taboola, Smarty Ad and so on, but all of them end up not delivering enough returns, and as a publisher, you end up going to google.