This was/is inevitable. The LLMs already know (and will know) language better than any individual human. They remember everything. Every word of Melliville, Shakespeare, Homer, Whitman, Toni Morrison, the bible, the internet.
The study validates previous research that has shown that people often prefer AI-generated writing in various formats, including short stories, poetry and essays.
Source: Do people prefer stories written by AI? | Cambridge University Press & Assessment