it takes 4 men to carry one wounded of the field, it only takes one to dig a grave, at least that’s how i remember this issue being explained, its simplistic, cause it doesn’t explains the resources that have to go behind taking care for a wounded soldier, but it’s close enough for grunts to understand
I recall the ratio being 7:1. For every 1 that had to deal with a dead body, it took 7 to deal with an injured soldier. That included doctors, nurses, people to fed them, rehab etc. Also, it is said that psychologically, a wounded man (screaming, crying, in anguish, pain, missing limbs etc) affected other soldiers more than a dead body.
The theory is not to kill your enemy but to tie up their resources and also to demoralize them.