Chat gpt is a terrible writer. At least, every example I have seen has had poor information density and was generally worse than the input prompts people used when they wanted to 'fluff up' a statement or opinion. I would be genuinely interested in a counter example.

Side note - your main point seems overly optimistic. How would we recognize, value, or design a 'sane' machine when by your argument we dont have access to sanity? Seems way more likely to generate a distillation of our neuroses.