For what it's worth, whatever LLMs do extensively, they do because it's a convention in well-established writing styles.

LLMs have a bias towards expertise and confidence due to the proportion of books in their training set. They also lean towards an academic writing style for the same reason.

All this to say, if LLMs write like you were already writing, it means you have very good foundations. It's fine to avoid them out of fear, but you have this Internet stranger's permission to use your em dash pause to think "Oh yeah, I'm the reference for writing style."

I think that bias is not due to the proportion of books and more due to how they are fine-tuned after the pretraining.

Aren’t books massively outweighed by the crawled internet corpus?