Who would build a helicopter that had insufficient yaw control in many situations within the flight envelope? Step up Bell helicopters...........
Aerospatiale did things differently - the Puma's infamous "yaw / roll divergence" caught out more than a few, too. The cross coupling from yaw to roll was strong enough to overcome cyclic lateral control, even on the ground it could catch out the unwary.
But that's why we pilots have to be trained to understand and respect the limits of the aircraft we fly - almost all of them (rotary or fixed wing) have their dirty little tricks to keep us on our toes.
