Right up front, I have no experience with NaNo.
That out of the way, I was reading this thread and feel that I do have to stick my 2 cents in.

There are two sides to writing that are essential to producing great writing.

The first is art, the second is craft.
The art is the inspiration, the flow of words, the "crap" if you will.
The craft is the careful and painful process of using all that you know to mold that "crap" into a finished piece.

The craft (the editor) should not, in my humble opinion, get in the way of the art.

Jay