To take the theory a little further, with pure rod dippers, as the RPMs go up, you reach a point where the dipper feed has not recoverd from the last "splash" and therefore the oiling becomes inadequate. In about 1939, Chevy added "dipper sprayers" that were supposed to address this problem. However they were miles behind the industry in this respect. Also, the babbitting on the rods was very thin and I would imagine exteremely expensive to manufacture.
