I don’t even think it blocks the channel long term from your recommendations. I’m pretty sure they’ve tried to sneak in an old channel I’ve explicitly said not to recommend again in my recommendations via whatever multi armed bandit with noise algo they’re running.
Don't want to give another extension access to read my screen though. Why do extensions require such broad access? Can't think of this needing anything outside the YouTube domain
Extension [1] gives a little 'X' beside the channel name in home and search, that can be used to completely remove that channel from all future searches.
Similarly, remove a bunch of random distracting crap[2] such as 'related results'.
Being able to subscribe to specific playlists and keep specific playlists from your subscriptions would be wondrous. There's a ton of channels I'd like to subscribe to but they just pollute my Subscriptions page too much.
You can add a playlist to your library and it will show up in the Playlists section. Navigate to the playlist and look for an icon with throw horizontal lines and a check mark.