It’s useful for gauging the general opinion on a subject, or for “exposing” fake affirmations without having to dig comments.

It does bring its issues, but I think the pros outweigh the cons. Plus it’s not like Reddit where you just have the balance, people indeed have the tendency to ignore/comment snarkily on “-5” comments, but if they see a “+10/-15” they often realize it’s a controversial opinion and might weigh in.