Building products is a different skill than writing about them. And if you write just "back of the napkin" people will complain about it even more than about an LLM version. Writing polished content is hard and takes a lot of time and skill.
People used to complain about back of the napkin posts because they signaled low effort. The same is true about LLM blogs. A back of the napkin blog signals more effort than slop.
A back of the napkin post means at least one person had interest in its authorship to put down their drink and write something, the LLM made blog posts are a show that zero people had interest in its authorship enough to put down some words.