Here's the mechanism. The model has read text from every perspective imaginable: CFOs, lawyers, teachers, furious customers. A good role tells it which of those voices to continue, and that character's standards, vocabulary and pet peeves come along for free.
That's why "world's best writer" is empty: there's no 'world's best' pattern to select, just a compliment. But "sceptical CFO" selects concerns Priya would have needed a paragraph to list: margins, assumptions, that suspicious 'miscellaneous' line. Watch the same draft go through both.