I'm not sure any emdash use at all is what people are calling out typically(maybe it is?), more the sheer number of them typical in LLM written stuff.

Just ctrl-f'ing through previous public posts, I think there were a total of 7 used across about that many posts. This one for example had 57. I'm not good enough in proper English to know what the normal number is supposed to be, just pointing that out.