It's a little different on HN due to how the comments are hidden quite quickly when downvoted. I frequently upvote people who reply to me but I disagree with,

It's a little different on HN due to how the comments are hidden quite quickly when downvoted. I frequently upvote people who reply to me but I disagree with, simply because it would ruin the comment chain and hey, they might just be right anyway ;) I reserve downvotes for rudeness and demonstrably wrong/misleading comments.