In case I trip on both of you, I meant that I did not know that - is em dash.
As for seeing the - in written works? I'll be frank, in my 2022 times reading in RRL and SH, I don't really see any authors use the - at all. After 2023 however, I stopped reading any EN works including TLs, so I can't be the judge.
No, I wasn't offended or anything, just casually mentioned in case you formed some huge misconception due to misinformation.
Em dash has been used in web novels for a long time cuz that helps in shortening the sentence. Authors just use it less cuz it's tedious to add through alt code.
While it is true that em dashes appear more frequently in novels with AI involvement, It is by no means a major indicator of AI generated novels.