question for BobCFlatpicker...

I noticed that most of the people who were flatpicking did not pivot the motion at the wrist... instead they moved their whole forearm from the elbow. Same for most mandolin players. Is there a reason for this? Strength of playing? More endurance? At first glance it seems to defy the idea of economy of motion... but it sure sounds awesome, so they must all be doing it that way for a reason.