The only explanation for getting rid of dislike count that makes sense to me is to make big brands happy as their videos can't be made to look bad with a high dislike count and they can't be "dislike bombed" for things that may be unrelated to the content (eg the recent Activision-Blizzard scandals).
Why? Because in every other way (and every way for the viewer), this makes Youtube worse. So it's a hell of a price to pay to appease big corporate interests. That's why I have such a hard time comprehending this move.
It definitely changes how people use the dislike button since there's no feedback for it. Maybe that too was by design? It's true that people are generally terrible at using dislikes and downvote buttons. Ieally it would be a quality indicator but really it's just used for "I don't like what you're saying", "I don't like you" or "I don't like something about you". And that's probably not a great signal.
Side note: for anyone with such functionality, it would probably greatly improve the overall user experience to identify these low-indicator downvoters and shadowban them. Don't take away the downvote UI. Just make it do absolutely nothing as in it shows them they downvoted / disliked but just don't count it for anything. These people are toxic.
Anyway, I actually hope to see more low-quality generated content on Youtube as it's probably going to be the only thing that causes this decision to be reversed.