Downvoting (from what I gather) is supposed to be used not as a disagree button, but rather as a tool when a comment doesn't add value to a conversation, hence why downvotes are so restricted on HN.
dang - https://news.ycombinator.com/item?id=17996858
PG - https://news.ycombinator.com/item?id=392347
Downvoting as a tool to show disagreement has always been standard practice here. Mini-modding on the other hand...