lemmy currently has a system for displaying upvotes. anything that has been downvoted will have the total number of ups and downs displayed next to the arrows. reddit used to have a similar system with RES, but they removed it for Reasons™
i don't think it's possible to sort by upvotes alone but that would be a good feature
I'm betting your instance isn't federated with group.lt. Not sure how it works on kbin but with lemmy you'd need to paste the url into your instance's search bar to get it working (or if you don't care about being logged in and able to comment on the page, you can just go to group.lt/c/war)