That's a good enough question that you've provoked me into figuring out what I think about this.
Adding words takes up space. A downvote doesn't. Therefore a downvote is more lightweight, therefore there are times when it's more appropriate than a comment. It's an in-between gesture, partway between silence and verbalization. I like that subtlety. It's an especially good way to express disagreement with something one feels is not only wrong but also somehow debasing. A comment doesn't have to be rude to be debasing, it can just be mediocre or somehow crass, nor is one always able to say exactly how. Those are cases where fostering more discussion is unlikely to do good and it's better to hold one's tongue. But downvoting still gives a signal to the original commenter as well as to other readers that someone's not ok with what was said. I think that's meaningful, and also that it's fairly rare to see people abusing that signal. It does happen, but more often when someone thinks they don't deserve it, it's kind of obvious to others that really they do. So when it happens, the best way to respond is with a touch of self-honesty. Maybe you'll come out roses but just maybe you'll notice something worth correcting.
One other thing about downvoting. I think what makes it controversial, and also interesting, is that it's an emotional expression. (Upvotes are too, but downvotes are stronger.) That explains why people get upset about it, have strong opinions and so on. But it also explains why it's a good thing to have around. There are very few emotional channels available to us that don't require proximity. It also explains why it's wrong to say that downvotes are inferior and should be replaced by comments. Imagine if people were forced to put every emotional gesture into words. It would be impossibly ponderous. And we'd end up talking about nothing else.
Adding words takes up space. A downvote doesn't. Therefore a downvote is more lightweight, therefore there are times when it's more appropriate than a comment. It's an in-between gesture, partway between silence and verbalization. I like that subtlety. It's an especially good way to express disagreement with something one feels is not only wrong but also somehow debasing. A comment doesn't have to be rude to be debasing, it can just be mediocre or somehow crass, nor is one always able to say exactly how. Those are cases where fostering more discussion is unlikely to do good and it's better to hold one's tongue. But downvoting still gives a signal to the original commenter as well as to other readers that someone's not ok with what was said. I think that's meaningful, and also that it's fairly rare to see people abusing that signal. It does happen, but more often when someone thinks they don't deserve it, it's kind of obvious to others that really they do. So when it happens, the best way to respond is with a touch of self-honesty. Maybe you'll come out roses but just maybe you'll notice something worth correcting.
One other thing about downvoting. I think what makes it controversial, and also interesting, is that it's an emotional expression. (Upvotes are too, but downvotes are stronger.) That explains why people get upset about it, have strong opinions and so on. But it also explains why it's a good thing to have around. There are very few emotional channels available to us that don't require proximity. It also explains why it's wrong to say that downvotes are inferior and should be replaced by comments. Imagine if people were forced to put every emotional gesture into words. It would be impossibly ponderous. And we'd end up talking about nothing else.