I started on HN four and a half years ago. My impression was that, in those days, HN had higher quality discussion. More of it was technical, but even the nontechnical discussion (political, say) was discussed differently. There was more fact- and evidence-based discussion, and less dogmatic assertion of positions. There was more real thought and less reflexive spewing of pre-canned viewpoints.
HN has become a lesser place - more filled with dogmatists (of various flavors), and less with people who can actually change their minds if given real evidence. As a result, the discussion has become less about evidence and data, and more full of strident statements of dogmatic positions, made by people who will happily talk but won't listen.
In that environment, of course you're going to get downvotes from the dogmatists when you question (or worse, contradict) someone's dogma. But is the strident stating of dogma by someone who won't listen itself worthy of downvoting? I'm not sure the answer is no - that's not the kind of "discussion" we want here. On the other hand, it may be reinforcing bad behavior on the part of others, and some of those "others" may be salvageable...