I think that when I throw a ball or skip a stone the rotation of the upper arm can supply a lot of the power used in the throw. I am not real sure though.
Actually with the stone skipping when using mostly the arm it is probably a key factor. Possibly those who actually do use an arm powered swing in golf the rotation of the upper trail arm is a key factor. I think you can see this if you swing with very little shoulder turn on the backswing.