Earlier quoted context omitted.
But they shouldn't. If there are people who want and like 75% of the videos I watch and like, I'd really prefer that YouTube avoid recommending me videos that those people have already watched and disliked. The only disliked that should be ignored are the ones where someone didn't even let a video load before hitting dislike.
They would only use liked videos to do recommendations anyway. So unliked and explicitely disliked should be treated the same. Incidentally I don't think I've ever used the dislike video button, if it's bad I just move away.
I rarely like or dislike anything, unless there's some significant reason to do either. The best example I can think of for when I've happily disliked something was the 2018 YouTube Rewind, which was absolutely atrocious a Google needs to understand that their creators are getting more and more reason to find an alternative to their ridiculously poor management relating to monetization and the algorithms.