Hmmm. You can't assume the desirability of background video always correlates to use of a mobile OS. It correlates more strongly to related factors such as connection speed, battery vs AC power and CPU speed. My laptop tethered and away from mains probably doesn't want background video. A docked high-end tablet probably does.
Grandparent comment may refer to basically never wanting such video (which is my preference). In other words, the "feature" of the implementation being broken on mobile should also be ported to desktops.
If websites cannot act responsibly and make video and/or audio click-to-play[1], they are going to be added to the killfile. "Adblockers" are also useful for blocking annoyances[2], not just ads.