This is less about "customer demand" and more about having to meet minimum video length for mid-clip monetization slots. Strictly an artifact of how YouTube works.
I didn't know, I pay the Premium to hide that stuff. Regardless, given the effort and lengths they went to, I'm happy to see them do so in a manner that funds their ability to do more.
YouTube know what they are doing… irritate the hell out of you until you buy Premium.
I once had YouTube on in the background and an advert which was an hour long popped up - but I was focused on something else and away from the screen and the tv remote.
The advert? A video of someone pointing a camera outside of a window during the night and onto a dark street (no sounds other than rustling from the person holding the camera). An hour long of it.