I'm baffled by people who says things like this. I make heavy use of both "Not Interested" and "Don't recommend Channel". They don't do as much as I would like (why oh why does Youtube insist on thinking I'm interested in obscure Rap/Hip Hop?), but I can clearly see recommendations shift over time. Marking any single video doesn't seem to do much, but marking 5-10 similar videos (mostly) does something.
Paid promotion (by channels) breaks past the barriers... It's part of the conflict of maintaining the illusion that sponsored content is what gets first placement throughout YouTube.
Its also maddening to content creators how newly upload content lists only feature paid promotional content every time. That's also exactly what makes certain (paid) content look massively popular over everything else, even when the production values are sub-par.
