Nick, as usual, is right on.
Most helicopters can only generate a steady load factor of 2.0 at most, and transiently not much more than that. The manuevers to get even that load level are pretty interesting, and not stuff that is normally done.
The interesting thing about the FAR requirements is that they are 'designed to' requirements, and no necessarily 'demonstrated to' requirements. The tail boom requirement is one that comes to mind.
The other issue is whether the fatigue spectrum the manufacturer designs to is what is finally used. Using a helicopter for logging is not the same as VIP transport, as we have found out in the industry to our cost.
But a great question.