Sometimes people hear "no" and they don't stop. They're told they can't get something published... and they publish it themselves. They're told they'll never get into a certain publication... and they keep trying until they do.
No can shut people down. However, it can also fire people up.
If you'd like to find out what being told "no" has done to me, check out my post on The Muffin. It might be some nibbling you'll enjoy...