The problem is that when people leave those bounds, they all-too-easily feel that they're doing it for principled reasons, and this is almost always false. They may not feel it, but it comes through acutely to others—especially to those on the side being attacked, who then feel entitled to react in kind. This is how we get a downward spiral. Each reacts to the shadow of the other, which appears as a kind of demon [1], and fails to see their own, and therefore feels justified and righteous. "He's causing the problem; I'm simply reacting." It's astonishing how often that comes up even in the mostly-trivial field of an internet forum.

I know these moderation comments can easily sound like "everybody please be civil and courteous", but that's not where we're coming from. Closer would be to say: be responsible for your shadow.

It's an open question how to process enough of one's shadow so that pure anger can cut like a sword in a clear way when called for. Most of us have work to do before we get there.

[1] more on 'demons' here: https://hn.algolia.com/?dateRange=all&page=0&prefix=false&so...