If you are in a group and a sniper hits someone that isn't an instant kill, what do you do? Take cover and let them die, or run in the line of fire and try to help or try to find the sniper?
You make it sound like it is intentionally done but if the shooter is far away/has poor accuracy and the soldier has body armor, chances are he will be incapacitated but not killed. After that the question is: is more morally ok to killed the downed soldier or wait for his unit who is still and active aggressor.
Because the hurt suffer a lot. Getting through life missing a leg is not pleasant. Also dozens risk their life saving a down but alive friend, while you will leave the dead until it is safe