This was a great post. Very easy to digest and lots of stuff to ponder on as my head slowly wraps itself around a few counter intuitive learnings.
For bench press, short arms are an advantage, as well as where specifically the muscle anchors in the limb. Similarly for squats.
For deadlifts, the situation's slightly different: long arms help in that the bar needs to be moved a shorter distance, though femur length still benefits by being short. There's also femur-shin ratio, and how that plays with angles.
But yes, volume vs. cross section matters a lot.