Yup, this baffles me too. The counterarguments seem to be that "you're gonna see autoplaying content anyway and this just makes the advertisers life harder".

I think Google added an option to disable all/most autoplaying content in Chrome a couple of years ago. But they quickly backtracked and removed that flag, claiming that it breaks in-browser games or something like that. It's a pretty weak reason for me, I don't care about in-browser games, I just want to read a news article without some irrelevant video popup distracting me, plus blasting audio.