Because not everyone knows everything, and the entire point of being HACKERS (I assume the uppercase is useful) is to promote learning and sharing knowledge.
So whilst this is probably not front news worthy of LEET HACKERS it's probably made someone go 'hey thats cool' and that's all it needed to do.
No, it implies that you think that the other person is stupid AND they use some form of Unix. Any way you put it, your response is unfriendly and rude. And Hacker News should not be known for arrogance. In fact, the person reading this article might not know much about tunnelling, but maybe writing the next greatest app. You won't know who you are displaying your arrogance to, so don't do it.
So whilst this is probably not front news worthy of LEET HACKERS it's probably made someone go 'hey thats cool' and that's all it needed to do.