> I'm sorry to the professional writers out there, but if I see an emdash in a piece of throw away writing (like a reddit or HN comment) I assume it's AI generated and I now immediately stop reading it.

All of this is distracting from the real question, which is:

Why do you care if it was AI generated?

As long as my comment reflects what I intended to say, you shouldn't care if I wrote it or the AI wrote it. Did it offend you in the past if an HN commenter used Grammarly to help craft the comment?

This is the literary equivalent of an ad hominem attach.