Very few humans go to the effort of using a true em dash in Internet comments (almost everyone just uses a hyphen), so it's a pretty good LLM indicator when paired with a certain writing style.
Until LLMs came around, I rarely saw other people use interrupting/parenthetical clauses at all, em dash or not. Kind of the same with semi-colons even. Or bold or subtle italics.
I’ve always enjoyed the style that em dashes and semi-colons add to a piece of writing and it was what made me start using them. It was always notable to me when I noticed them in someone’s else’s writing, which was always rare.
But definitely not none— I use them in comments all the time, and have for decades. I find asinine observations conveyed with repetitive, circular wording to be a better indicator.
