And it's seemingly the only large platform where you have some control over the 'algorithm' - meaning if I tell it I'm not interested in something, or not to show me content from a creator, it actually works. On Facebook or Instagram the "not interested" button doesn't seem to do anything and it takes several clicks and a wait to block an account.

Is it? I've heard YouTubers make snide comments about subscribing "as if that has any bearing on whether you see my videos", implying that it has minimal impact on the algo.