True, but the main point is still the difficulty in the representation of two different parts of the body being able to take the same hit and suffer more or less damage respectively. I'm reminded of the body-charts from Deadlands (or any other RPG with a body-target chart) wherein certain parts of the body take increasing damage and can potentially one-shot your character when their damage is maximized. If you're not familiar, in Deadlands each body section has a fixed amount of HP and your die-roll represents which body part takes damage. Maxing the damage to the leg or arm can result in a "dead leg" situation, damaged beyond repair but still attached or completely severed, depending. But if the gut, head or chest take maximum damage, you're DEAD, boom right there dropped DEAD.
Shock and blood-loss are well-represented by the SSSoD system of death saving throws already.
I'm just saying that for a system like D&D 5E where the game doesn't (generally) pay attention to hit locations, it's probably not worth adjusting the damage based on where the creature is attached. Especially since losing your leg (or even just having the femoral artery punctured/severed) can make you just as dead as your friend accidentally stabbing you in the eye could.