This is a Nazi's wet dream, because they have always been enemies of thought, and now they have a machine that eloquently sells their animalistic ideas.
Maybe it's where I browse but I haven't really seen any accusations that well written content is LLM generated. Language models have a rather specific tone they like to use, and it's relatively easy to distinguish once you've learned those patterns.
I have seen, however, blatantly LLM generated text going undetected.