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.
I would like that. Or even a scheme where they can collect data, but it's stored on my local computer so I can edit it and delete it (granted I know there's a ton of issues with that, but there is w/ the current scheme also)
Just let the users set their own advertising profiles! Always relevant ads, no tracking needed.