In a snatch grip high pull most of the power should come from the hips and legs. You should be creating to much acceleration with the legs and hips that hte barbell is moving up due to acceleration for at least half the range of motion. The arms should only be the finishing touch.
Furthermore, due in part to the grip width used in the snatch grip high pull, the shoulder externally rotate a bit at the top which prevents shoulder impingement than you can often see with upright rows.
A snatch grip high pull is NOT an upper body lift, its a WHOLE BODY movement that should emphasize the hips and quads if done properly.
The only injuries I’ve seen on high pulls are in people pulling predominantly with the arms (either starting the pull with their arms or using mostly arm strength to get the weight up). I’ve done 400lbs on the high pull, do you think I could pull that with my arms???