That's the unofficial rationale. Another theory is low wrist allows limp-wristed guys to draw more weight than high wrist without the inconvenience of training and strengthening the wrist. Just as much baloney as the other, IMO. The REAL reason: Low wrist naturally puts a bend in the elbow and gets your arm out of the way of the bowstring on a bow with low brace height.

The bad thing about low wrist, bad for short draw archers anyway, is it reduces your draw length by at least an inch. Less draw length, less speed. Assuming we lose only an inch, shooting low wrist on a 27" draw bow with 7" brace will give you the same power stroke, same energy, same speed as if you shot high wrist on an identical bow braced at 8" but 28" draw.

I shoot high wrist with the only part of my palm contacting the grip being the web between my thumb and forefinger. My opinion is the more hand contact you have with the grip, the greater the chance for grip induced torque. I have never felt fatigue in my wrist or forearm. The bones are compressing against themselves under load of the draw weight and support the weight with no muscle tension involved, whatsoever.

I've tried the low wrist/bent elbow style, certainly. Had to follow the latest techniques and stuff. Found out it puts a good bit of muscle tension into my triceps and forearm. The low wrist style is much more fatiquing and 'torque-y' than high wrist, for me. I can't shoot for beans that way.

Edit - DANG! You guys were busy whilst I was typing! Trushot, if you haven't fine tuned your bow's tiller, then you need to do so. High wrist with a small contact point on the grip does make dynamic tiller adjustment more critical. Adjust so that the bow stays level throughout the draw cycle, not rocking forward or backward.