The comment regime on HN is broken. Down voting is anonymous & carries zero social cost. The fact of a homogenous karma space is a contributing factor: user x /may/ have gained karma points based on input on subject matters that have nothing to do with the topic at hand.
And I agree with you regarding the real world karma consequences of this for HN :)
HN is very important, but it is also greatly neglected. I'm not sure if the goal is not to compete with some of the startups or if Paul Graham has some future plans about it. Unfortunately, due to loyalty, people keep sticking in here even if better alternatives pop up from time to time. Some of those being Lobsters [0] and Monocle [1].
And I agree with you regarding the real world karma consequences of this for HN :)