What is the purpose of the dislike button if you can't even see the dislikes?

I know right. There is no point.

Ignore the comment....

Engagement. They know you'll interact with comments you don't like, so they'll show you more videos with comments like that, so you'll keep watching and commenting and interacting. That's my guess at least

From my understanding if you dislike a comment and enough people do, that person’s comments will eventually end up as “folded” where they eventually become auto hidden.

Same reason the report button exists, just so you feel like you're doing something but you're actually not.

I genuinely don't think people even dislike in the first place because if they dislike what somebody says, they'll just reply. You should just give that person a piece of their mind. And as far as I know and I could be wrong, I don't even think the person you dislike can even see a dislike on their comment. There's no notification for it, and I don't even think there's a way to look at it in any other settings or something.