That same critique should first be aimed at the topmost comment, which has the same problem plus the added guilt of originating (A) a false dichotomy and (B) the derogatory tone that naturally colors later replies.
> It's reasonable for even good writers to not know how or not care
The text is true, but in context there's an implied fallacy: If X is "reasonable", it does not follow that Not-X is unreasonable.
More than enough (reasonable) real humans do add em-dashes when they write. When it comes to a long-form blog post—like this one submitted to HN—it's even more likely than usual!
> the extra keystrokes
Such as alt + numpad 0150 on Windows, which has served me well when on that platform for... gosh, decades now.
Where do you think the training data came from?
Incidentally, I turned this autocorrection off when people started associating em dashes with AI writing. I now leave them manual double dashes--even less correct than before, but at least people are more likely to read my writing.
en dash: https://www.compart.com/en/unicode/U+2013
em dash: https://www.compart.com/en/unicode/U+2014
Edit: Ah, Libreoffice does have a built-in autocorrect for em dash, but you have to type this:
:---:So ":---:" does work for the em dash? I thought something with fewer keystrokes work, too, at least I remember the em dash from less, but perhaps I just typed it so quickly I did not realize it was indeed ":---:".
This article does not appear to be AI-written, but use of the emdash is undeniably correlated with AI writing. Your reasoning would only make sense if the emdash existed on keyboards. It's reasonable for even good writers to not know how or not care to do the extra keystrokes to type an emdash when they're just writing a blog post - that doesn't mean they have bad writing skills or don't understand grammar, as you have implied.