This isn't as universally true as a lot of people seem to think. I'm not defending this particular article, as I haven't even read it yet. However MS Word has been auto updating a dash to an em dash for years. Where do you think AI got it from in the first place?

It can be a marker for text that is written in places where plain text is preserved. In a written article that most likely started as a word document? Not always the case.