Further, I believe the GP was referring to HN, which has, like reddit, a one-dimensional voting system (for the most part).
In any case, I'm much more hesitant to down vote here just because I disagree with an opinion than on Reddit, and I think a lot of people do the same. To me, that higher standard for what's both considered a good comment and what's acceptable are what makes HN more useful for interesting discussion. There are probably 5-8 aspects of comments that could be voted on, but what we see with these singular rating systems is that the community forms around what is acceptable and what is not, and people generally fall in line with the community norms (both in submissions and in their own rating of others). Reddit is interesting in that I've noticed that this community norm is somewhat malleable based on the subreddit. /r/gifs and /r/programming have a distinctly different feel in the comments.
I don't think any of this sentence is true. Getting [dead]ed was an experiment a long time ago which afaict ended quickly. And bans for non-spam-related reasons are obviously quite public.