Take a look at the grip configuration over time. The Trapdoor Springfield, Krag and Springfield 03 all had straight grips which necessitated a high elbow to help wrap your thumb around the far side of the grip.
That
sounds good, but I don't quite see it. I just tested with my Monte Carlo and with a mil Springfield. Mounting either with a high elbow certainly guarantees a good 'wrap', but going in low doesn't at all prevent it. (Though I can see how trainers would go for a 'guaranteed' way rather than have to continue correcting those who failed to grasp enough around.)
Citations would help keep the answer out of conjecture and in history.
