I have flown both Aerospatiale (3500 hrs) and Sikorsky products (1500 hrs), both military and civilian types. Each of them have good points and some not so good points..
(I also flew a Robinson helicopter. Only once and I have since had no desire to do so again).
If mud is to be slung about it could be done at any manufacturer, for a variety of reasons. However, as a professional pilot and Military taught QHI I do not see jack stall as a design flaw but merely as a limitation. It has already been pointed out that jack stall only occurs outside the normal flight envelope under high power and "G" (I have seen a roll off the top in an AS341 without experiencing jack stall - surely that is enough for most pilots and engineers)? The phenomena is preceded by warning signs including a big increase in vibration. I would far rather the aircraft calls "enough" by stalling a jack than something else letting go instead, either on that occasion or later for someone else to deal with.
Jack stall is just like a heart attack - it's nature's way of telling you to slow down a little...