It was suggested at a FIE standardisation meeting some years ago, by a fairly senior former RAF QFI that the practice of using rudder at the point of stall came from training on the Harvard. When the aircraft dropped a wing, the weight of the engine lead to increased yaw and the use of top rudder in the recovery would minimise the height loss. Unfortunately, this technique was passed on to many new instructors, who were trained in the 60s by FIC instructors who might have been trained on the Harvard.
Following a rather nasty accident in a Slingsby involving "oscillatory stalling" the practice of trying to pick up a wing with rudder was discouraged by the CAA.