To whom? To advertisers, and the creators, of course. To viewers? How does that help inform me if I'll like it?
If you're looking for a tutorial, and one video has 5000 views and 4000 likes, the other has 5000 views and 2 likes, that really doesn't help inform you about which video might solve your problem better?
If I knew why people didn't like it, perhaps. Videos get liked or disliked for all kinds of reasons. Typically I'll find several tutorials that look like they may be relevant based on the thumbnail and title, and then skim through each one very briefly to see if it looks as though it is what I'm looking for.
Likes to dislikes is an even better signal. Shame on YouTube for removing that.
You can actually use a browser extension to show it still. The dislike count is still available, just not shown.
I've heard that it's not actual dislike count, but extrapolated data contributed from people who installed the extensions. But I've also heard that some channels have compared it to their actual dislike count and it only differs little.