It’s not just the em dash—it’s the juxtaposition.

Nobody types em-dashes.

I do! Alt-0151 on Windows. I'm not an AI, though... (and you can also write in Word and copy-paste here)

this puts you on a desktop with a full-size keyboard or a laptop with a numpad then, which is a very small minority these days with a definite dev-centric skew.

On many Android keyboards you can press and hold various keys to get access to many of the "extra" punctuation characters and fancy "foreign" letters. I imagine the same is also true on Apple phones as well.

Indeed I am, but the point here is that some users are actually typing em-dashes outside word processors or publishing/typesetting tools (e.g., on HN)—so it's not necessarily a sign of a message written by an AI (m-dash pun intended). The poster could as well be a developer with a full-size keyboard.

People with iPhones do. If you type a double hyphen on iOS — it is replaced with an em dash. Three periods also become an ellipsis…

iOS autocorrects -- to an em dash. I do it a lot.

Though true I would have spaces around it.

on Mac its super simple–option + (minus)–so I use it all the time.

I do. I also type en-dashes where appropriate, and ellipses, and balanced quotes.

i only type balanced quotes and parentheses because otherwise GCC will get mad at me!:

edit: failed to compile. missing semicolon

I do. One of the first customizations I make on a new Linux install is mapping the compose key—em-dashes are then <compose> followed by two dashes.

On Mac, it's configured by default: <option>+<shift>+dash

It would really be disappointing if typographic pedants start being falsely accused of being AI.

I do—daily, too.

I do—commented on another thread, but:

  On Linux (maybe only certain distros, not sure) the keys are different, 
  but you can enable a Compose key and enable special character keybinds as well.
  
  For example on Mint:
    en–dash is "<compose> <minus> <minus> <period>"
    em—dash is "<compose> <minus> <minus> <minus>"