This is logical, but it’s also a lemon market. You don’t know the author, editor and publisher did anything of the sort, unless you’re the sort of person who doesn’t need the book. But if you do see an LLMism, it’s a strong sign of cost-cutting.
We should just be judging writing by its quality. There were always bad writers who wrote like LLMs or worse. It takes a lot of practice to write well.