This exists, doesn't it? "Block channel" (or rather, "Don't recommend channel") is probably the feature I use most... I must have thousands of thousands of channels on that list.
The alternative is "Not Interested", but at least on AppleTV you're forced to then choose either "I've already watched the video" or "I don't like the video", and I have literally no idea what to do with those choices. If I've already watched the video then the reason I'm saying I'm not interested is because I didn't like it, so both are true, but I can't select both; and if I just don't like the clickbait thumbnail or title I haven't watched it and I don't know if I like the video itself, so neither is true, but I can't select neither...
Every time I think about YouTube's interface it becomes more obvious it's made by people (?) who's brains just don't work like mine...