What is it about the higher let-off that makes it so hard to shoot and dangerous? Is it the fact that you are not actually holding back any weight?

I would imagine that if you unknowingly creeped forward a little from full draw this thing may pull your arm out of socket. With no " forward" pull or weight to hold back I could also see a person trying to over draw or pull to hard against the back wall, almost pre-loading the limbs.