the books the LLM were trained on that used the most em dashes used like 1 every 200-500 characters. LLMs use em dashes at a rate of like 1 every 40-50 characters. It's not even CLOSE to human behavior.

There are no absolutes, some people do spend lots of time and effort to put cool looking emojii characters into their documents which kill portability and cause all kinds of problems down the road. For the LLM it's 0 additional effort, in some ways less effort because the emojii is a kind of compressed information - but it still causes problems when moving around to different editors, different toolchains...