Um, but take your typical orc tribe. Wading through that mob, some 90% or more of them will die from a singe attack, no matter how small the blade or wound. Clearly there has been no attempt to simulate our objective reality there. Rather, what they've done is simulated a certain type of movie....but is this necessarily a problem?
If you like Hong Kong martial arts movies you'll probably have no problems at all. If you're strongly attached to the style of play in previous versions of D&D or you want to see things as being a simulation of our objective reality, maybe you will have more problems wrapping your head around this shift in the game.