My jealousy is immense. After a worldwide scientific study, it was discovered that I am the worse reviser of all time. Just can't stand it. Hell for me would be going back over everything I've written and trying to tighten it up on painful deletion at a time. Kudos then, because they say that the best writers are the best revisers.
...I'd say (as a non-writer but with some non-fiction editing experience) that both of you are right. I believe there is such a thing as a natural, fluent voice that makes a direct trip from brain to page. Often spontaneous. Often untutored. And then there are people to whom it doesn't come so easily - but who have the patience and reflective capacity to revisit and polish their work until it shines. In either case, there's a role for an editor whose input may range from verbal feedback to a hands-on rewrite. As Donne observed, "No man is an island..."