Wouldn't realistic damage be rather hard to code?
For realism, a game would use the amount of blood in someone's body instead of a health bar. Below a certain amount of blood, the player faints, and can be revived by bandages and a transfusion before they bleed to death. Being shot in the heart once causes someone to die within seconds, with subsequent shots reducing their lifespan further. A headshot is an insta-kill, barring occasional lucky players who get their skull grazed and are knocked down, but survive. Shots to limbs can disable the limbs, but the bleeding can be stopped by bandages.
I personally think this sort of gameplay would be very cool, but it's harder to make. It would take various independent hitboxes to keep track of what vital organs are hit, and the system would be even more complex if you wanted to keep track of bullet ricochets through the body. The current system in video games treats bodies as spongy sacks that take set amounts of damage when shot, which is ridiculous.