It seems that there is such regulation in place, in the US at least. But regulation regards average loudness throughout the ad, so you can blast away if you compensate with silence.

I don't normally really like the YouTube channel Cheddar, but they recently had a video on this topic: https://www.youtube.com/watch?v=tmydvmxWUsE

Apparently its FCC regulation (I'm not in the US), and the FCC cannot create legislation for streaming services so they are currently free to do as they wish.

Yes, that sounds right. Louder than the damned show you've just been watching.

TV stations should not allow that, or we should be able to counter it with technology.

Having said that, less of an issue now with streaming.