+1, as the kids say. Roger Angell, who knows a thing or two about writing, once said this:
writer needs a good editor. All of them, even the best. It's
interesting that the older and best-known and most professional writers
are the ones who really appreciate an editor. Young writers are
terrified. They think, 'What I've done should not be touched.'"
will also venture to observe that in these "I don't need an editor"
discussions, the writer is probably thinking only about things like
minor grammatical errors and typos. Whereas editing encompasses such
issues as identifying who exactly the writer is talking to, and why they
need the information; whether the information is being presented in a
logical and useful order; whether it contains fluff or obscurity, or is
simply incomplete; etc.