One of the highest priorities for the HN algorithm is to promote good interactions and discourage bad interactions. The logic is if you have a lot of people bickering with each other, regardless of the topic, it normalizes bad behavior. HN is trying to sustain itself as a forum with great discussions, so it very intentionally downranks anything that looks to the algorithm like it has people bickering with each other (eg. Up vote/down vote wars as a proxy for disagreement). Yes, this means many important topics move off the homepage because there is lots of disagreement within them. Encouraging good discussions is consciously viewed as more important than any individual topic.