It's the combination of a short torso (limits muscle mass somewhat compared to the same development over a long torso), short humerus (not long enough to hold considerable mass in the triceps) and long forearms (triceps need to work harder than usual)
But that's not really an excuse anyway. It's just what I was born with and what I have to deal with. I am not suited to squatting either but still mange to put up decent weights. But basically I just need to bro it up. Neurological efficiency is all well and good when you have a considerable amount of muscle mass but trying to develop it when you don't have a good base of muscle mass is fucking stupid. I'll post my back at some point, a proper lat spread- that is why my deadlift is good lol