But you don't need to run a giant spying system to make that happen, so the companies whose moat is their giant spying system don't want to even try that. They

But you don't need to run a giant spying system to make that happen, so the companies whose moat is their giant spying system don't want to even try that. They also happen to have all the users/eyeballs (they need them for their spying system, in addition to serving ads to them). So it's hard for anyone else to try it to see how well it works.