[XorNot]

Which would matter but the entry box in no major browser do was this.

The HN text area does not insert em-dashes for you and never has. On my phone keyboard it's a very lot deliberate action to add one (symbol mode, long press hyphen, slide my finger over to em-dash).

The entire point is it's contextual - emdashes where no accomodations make them likely.

[bee_rider]

Is this—not an em-dash? On iOS I generated it by double tapping dash. I think there are more iOS users than AIs, although I could be wrong about that…

[Duanemclemore]

Yeah, I get that. And I'm not saying the author is wrong, just commenting on that one often-commented-upon phenomenon. If text is being input to the field by copy-paste (from another browser tab) anyway, who's to say it's not (hypothetically) being copied and pasted from the word processor in which it's being written?