I've had a few comments downmodded, and it sent a clear message: my comment was simply not valuable to the people who read it. I use downvotes in the same way.

I've had a few comments downmodded, and it sent a clear message: my comment was simply not valuable to the people who read it. I use downvotes in the same way. There's many factors that contribute to a comment being valuable: factualness is just one of them. Poor commenters defend positions without evidence; try to cast personal feelings as rational arguments; fail to properly read and understand the article; attack an imaginary slight from the parent poster. In a real conversation, I'm not going to rebut everything disagreeable that you say: sometimes I'll just frown, turn away, shrug, or interupt you. Downmodding is my way of quickly saying that I didn't get anything out of your comment.