Sincerely, HN Guidelines Police :-)
Only problem is, Hacker News is full of thin-skinned, perpetually offended whiners who have never seen a comment they weren't somehow triggered by.
Now apply that to the n people reading a given post or comment! If those commenters try to communicate on what they think is "fair game" for the given conversation, then two comments deep in and you might already be at a 7 when the author thought they were at a 3. In more extreme cases, two people could misunderstand each other through text and simply go from a 1 to a 7 in a single comment, spending the rest of the time shooting back loaded replies at each other instead of thinking about the topic together.
It's a very human reaction we all tend towards, even when we set out our intents to do the "always reply with..." mindset instead of a tit-for-tat one. That's why I always start with the ideal approach - I can count on myself to help foul it up :D.
So I find myself being more sympathetic and SMH than antagonistic..