I have always found this complaint quite odd. Em-dashes are great. I use them all the time.

Never spent too much time thinking about em-dashes. Writers I like probably use them all the time—again, never really thought about it.

There are many other language model artifacts that are genuinely shite and are worth criticizing. Though, come to think of it, they have been getting stamped out with each iteration in model. Used to spend a lot of time trying to get models to refrain from words like "crucial".

What I do find strange is how the latest SOTA models appear to write with contractions by default, which began sometime in the past year. Anthropic models, in particular.

LLMs partially ruined em dashes for me, but I still use them.