So you write your novel, rewrite it, rewrite it again, and polish it until it gleams.  Then you put together a proposal and send it off to a publisher.  They ask to see the completed manuscript so you give it one final polish and submit it.  Its accepted and you do a happy dance, convinced that you and you alone have manged to compose the perfect manuscript... 
...until you get the edited manuscript back and see hundreds of red marks denoting corrections.  When I first thumbed through it I had a serious flashback to grade school, namely getting my spelling test returned with the same type of red marks. 
It's a humbling experience.