You couldn't be more wrong.
http://www.youtube.com/watch?v=fEQJAgIxX2A
Watch any number of the pitchers THROWING the weighted baseballs.
I have worked with many kids who have done the NPA program, and all of them throw 3 oz to 2 lb balls on TOP of the holds. Go to 9:30 in that video and see them throwing underload balls as well as doing holds.
Also read Dr. Coop DeRenne's studies on this topic that were done decades ago.