There are significant limitations to this way of thinking.
Navezgane is in Arizona while random gen may not be (it could be whatever your imagination accepts). Also, crafting imposes many suspensions of disbelief to be able to manage resources in a way that doesn't require YEARS to build a base (realistic, sure, but not all fun). And there are countless other examples of situations that might be realistic but certainly are not fun. Breaking a leg, a real possibility in many situations, would mean a long-suffering death for most people in this apocalyptic setting. Running around in bare feet to start (or even cloth slippers) would certainly mean getting cuts and bruises that could lead to infections. Getting an infection could itself be certain death in this environment.
It's not at all realistic that your average person could make a forge and then use scrap bits of brass to make usable bullet casings, combine them with lead chunks and gunpowder and make a bullet that won't explode in their face when used in a gun. Maybe 0.001% of people on the planet could pull it off.
Net result is that there has to be careful consideration on how you balance realism with "fun to play". I don't really find changing diapers enjoyable but when my kids were young I had to do it anyway. Just because it's based on reality doesn't make it fun to do or simulate. Compromises have to be made.