I think the downvote was because the comment doesn't really contribute anything... I am not saying I agree with this, but in the past I have seen Dan say things to people in the comments section when they seem to say "good post" on every's post without even mentioning the content. He is probably believing (whether rightly or wrongly) that the person who replied that way didn't even read the post and isn't contributing anything meaningful to the community. Maybe look and back and see if this user was ever warned before the downvotes came in...