Netflix never gave me a popup or played recommendation of anything between two episodes of a series.
I think that's what most people mean. They want to listen to an album/several/playlist and not hear anything else. (should add: and also not see any popups. Netflix doesn't give me popups, the only place I see stuff I do not want to see is the landing page)
That's so much worse than actually YouTube though. If I've been watching programming, physics, or history YouTube it absolutely surfaces excellent creators I'd have no other means of discovering.
YouTube isn't Wikipedia. I don't go into it wanting a specific narrow thing. Like how do you even find content you'd like otherwise?
We're approaching the One True User Interface: search bar and recommendations. And it's awful.