Youtube creators get access to watchtime stats which show a dip for sponsored segments. My understanding is that sponsor contracts typically don't ask to get access to that data though, instead they look at views and refferals

Hey, are you interested in whey powd... <skip> I guess not. And often it is the same sponsor in multiple video/audio. No, I am not interested in Crowdstrike. No, i don't want to become a Lord by owning a small amount of land in Scotland. Yes, I know about Ground News but I won't need it and yes, I know you can cheaply buy whey powder, add some flavor and hype it up.

And yet, HN (a text-based website) has advertising. It is a small headline in the list. Do people block this? I don't, and I am quite an adblocking person.

I actually believe billboards are a net minus for public safety. Just like you wouldn't want all kind of unnecessary traffic signs.