[TheDong]

If other people buy into this idea, then every site will begin proxying third-party javascript.

If the only way to get trackers on the average person is to serve it from the same first-party domain, or to bundle it in with the giant 'app.js', you better believe they'll do that.

Right now, the fact that only a small fraction of people run adblockers, and an even smaller fraction block javascript, is what allows it to work.