There's no point in the downvotes because...

Comments are more meaningful than upvotes and downvotes. I mean, if you get upvoted but no comments praising it, it's pointless. If you get downvoted but people never tell you why you're wrong and why they disagree, it's pointless too. And besides, people have choices whether to be rude or not, so they can make a comment that you won't realize it's critical to you

Comparing it to 5 star reviews? It's hard to compare and that's different because if you want to give a feedback comment, you're forced to use a star number and the purpose of it is for products

YouTube? Well even if dislikes are removed, you can't make use dislike extensions, you can make a comment or go make a hate video

A comment or post getting death threats? Like I said downvotes are pointless but comments are meaningful so you can go remove it

It sucks some subs encourage karma (certain upvote number) when posters will still just spam posts anyways