YouTube is a really bad example, watch one video about one artist, the feed will be full of just exactly that artist. And one can’t get rid of those “recommendations”.
But the same is true on most other platforms. It’s even worse if you are somehow specific. If you look for a specific premium brand, it will still recommend low-end stuff. If you are left handed, it will still recommend right handed stuff.
How does this really convert well for the platforms? What seems to prevent everyone to show users good, useful relevant recommendations?