Of course, not that simple. In the future, every other website will ship their own rendering engine (from some big CDN, of course) that prohibits you from mess

Of course, not that simple. In the future, every other website will ship their own rendering engine (from some big CDN, of course) that prohibits you from messing with their precious spam. Heck, I honestly do expect some startups doing just this kind of "innovation" as soon as WebAssembly gets slightly more polished and cross-browser, so probably just another year or two from now. (That shit will be fought with AI/ML nextgen ad-blockers, that would try to "see" what that positioned <div> is - a spammy modal or some legit navigation sidebar... and I don't dare to think any further, as we approach the singularity.)