Even without the meta-moderation aspect, just having multiple dimensions for evaluating any given post is so useful and seemingly unique.
"Upvote/Downvote" is not nearly as useful for ranking as the range of, say "+1 Funny, +1 Insightful, +1 Agree, -1 Disagree, -1 Spam, -1 Flamebait/Troll" (I've forgotten exactly what set /. uses)
"Upvote/Downvote" is not nearly as useful for ranking as the range of, say "+1 Funny, +1 Insightful, +1 Agree, -1 Disagree, -1 Spam, -1 Flamebait/Troll" (I've forgotten exactly what set /. uses)