> adding a pain-in-the-ass hurdle like "has to be hosted on the same domain" that 99.99% of people won't see the value of or understand is only going to hurt adoption of the better solutions.

Right, but that's my point—this is not a situation where visitors have to hope that site owners will be responsive to their preferences; rather, visitors are in a position to enforce their preferences via ad blockers, so there's no incentive for them to compromise on matters that, however poorly appreciated or understood, genuinely can affect security.

agree - but that gets to the larger point that mass adoption of anything like has to be fairly frictionless.

We are barely getting a third of people to use adblockers - you'd have to squeeze the ad server industry a lot more to make them change. How to squeeze them? Get more people to use an adblocker that enforces serving from the same domain. How to get more people to use an adblocker? Make it frictionless, like enabled by default on browsers.

Then by squeezing them, they would be forced to respond by building tooling making it more frictionless to serve ads form the same domain, etc.