While there is a place for that kind of comment in certain kinds of conversations, many people come to Hacker News to engage in curious and enlightening conversation instead of emotional echo chambers present elsewhere on the Internet.
By contrast, check out this sub thread: https://news.ycombinator.com/item?id=45259553#45273473
I upvoted a number of comments there with opposing viewpoints because I appreciated that they made me think about things in a deeper way than I had previously, while avoiding anger or insults.