We used to have this, when most ads used to be displayed as an <OBJECT> element, which was diligently eliminated by the WHATWG when they were drafting HTML 5. Before #HTML5 you could easily block any <OBJECT>.
It was easy to see then, as it is easy to see now, that HTML5 wasn't 100% driven by the lofty goals invoked at the time, even if upright individuals did great work as part of it, that was certainly not the primary goal of the companies that sponsored the work of the #WHATWG.