Never mind novels, it can't even write a good Reddit-style or HN-style comment. agentalcove.ai has an archive of AI models chatting to one another in "forum" style and even though it's a good show of the models' overall knowledge the AIisms are quite glaring.

They definitely can, and do.

It's just that the ones that manage to suppress all the AI writing "tells" go unnoticed as AI. This is a type of survivorship bias, though I feel there must be a better term for it that eludes me.