I don't understand why people continue to use em-dashes. As far I know, the comment system on HN doesn't offer them. And iOS and android don't make them a default. They aren't something normally used by humans because - is a keyboard option that's easier to use.
The usage of them immediately makes your commentary suspect. Either you aren't using the standard web interface to make a comment, you're using and odd 3rd party client, or its LLM generated.