> Sam's article talks about not directing gratuitous negativity at people when you're arguing with them.

Correct. That, plus not being gratuitously dismissive of others' work, like https://news.ycombinator.com/item?id=9314065 was. (I don't cite that to pick on a particular commenter; some users said they would find examples helpful and it's a random recent one.) Substantive, respectful criticism is of course fine and valuable.