That's vastly more expensive, though. Now you have to run extra servers to make outbound connections to the ad tracker's API server instead of turfing off all the work to visitors. It would be enough to significantly affect the ad market.

Oh no!

I don't think it's that expensive to do. All it takes is one well written package that is easy to install and this will be come standard.

I could even see a data broker centralizing this and distributing tracking to all of their clients. The client would just need to communicate with the central broker, which is not hard at all.

This setup already exists, they're called Supply Side Platforms.

As long as your scale is tiny, sure. At a point you'd need to turn that into an async task queue etc etc.

BTW, I see this as a feature, not a bug. I'm glad it would be harder and more expensive to violate my privacy.

You also get to do it on your fast cloud backend infrastructure instead of the end-users home computer and ISP. They will appreciate the increase in page load speed and overall responsiveness, and as a bonus they can't use ad blockers or hostfile tricks anymore.

That's also quite the possibility, and supports my point.