I understand where you're coming from. I likewise want people to feel like they can discuss issues that are important to them. And I can also understand why people often respond passionately and possibly uncivilly in response to what they perceive (and sometimes objectively is) incivility. That said, I don't agree with it. It's just not effective in the vast majority of cases, and I see the severe polarization in the US as partly due to this lack of civil, charitable discourse.
Would you and I be able to have continued this discussion (which I feel is civil and constructive, and I thank you for that) if we weren't taking care with how we express ourselves? I personally doubt it. For my part, I haven't felt that I've gotten heated or needed to restrain myself or rephrase for tone (as opposed to clarity), which I most definitely have in other discussions on divisive issues (in this case the role of civility in discussion of contentious issues). I sincerely hope you feel similarly, even if you ultimately disagree with what I've said.
Regarding downvoting: I believe it's off-topic here to discuss the proper use of downvoting. There's plenty of that to be found on HN already. In my comment above I'm describing the behavior I see: the positive as opposed to the normative. I do have opinions on the matter, but they're similarly off-topic.
I'm not sure what else I have to add on the topic of civility and discussion. I often reference the Principle of Charity[0] and Rapoport's Rules[1] as I personally find them useful in guiding my approach to discussion. Thanks again for your thoughtful discussion. I appreciate it.
[0]: http://philosophy.lander.edu/oriental/charity.html
[1]: https://www.brainpickings.org/2014/03/28/daniel-dennett-rapo...