The above illustration is good,it shows principles,but I'll point out the obvious.
There are a lot of variations on skeletons. My elbow reaches the bottom of my ribs. My hip bone is 6 in lower.I'd have to contort my bones out of a good natural stack to put my elbow on my hip.
I do benefit from having my upper arm rest on my ribs...but some shooting disciplines require daylight between the arm and the chest.
Folks,I don't even claim to be a good shot.
But note,in the above pic,the comb height,raised up to her face. The buttplate dropped,
She offsets her weight some to counterbalance the rifle, A more massive upper body would require less offset.
She still has her bones stacked natural,head and shoulders erect,nd the rifle is brought to her face.
My foggy brain might have this wrong...please set me straight if I am,but the folks who shot Scheutzen style,offhand,lead bullets,black powder,false muzzles,and muzzle loaded....Shooting with a Pope barrel,or a barrel made by a handful of men who were Pope's peers,
Were shooting in the range of 2 MOA at 200 yds.