a) diamond city is dope

b) nuclear war is extraordinarily underappreciated. like 0.3% of the former population is dwelling in a tomb, there literally haven't been enough people to clean up the trash and loot all the stuff. the fertility rate and life expectancy are rock fucking bottom. and fallout is optimistic about what humanity could do after global thermonuclear war. most analysts are going to be surprised a viable population survives the collapse, fallout, and famine at all.

c) i think the fire and radiation would put a pretty severe damper on the capability of natural processes to overgrow and degrade the ruins---which also have shittons of metal and concrete in them which have a life expectancy well over 200 years. ecological collapse will have fucked over the termites molds and bacteria so now a structure that should've rotted might stand up decades longer

d) the energy/powerlines stuff is waved away by miniature modular nuclear technology. a tiny fission/fusion reactor could keep a light on a loooooong time, though any lights people weren't actively replacing should be out

I feel like they were SO CLOSE to things making relative sense in FO4. It's established that the Institute went west and found out about the Enclave (that's how they have super mutants, they got the FEV from the remnants of Mariposa instead of just having another completely different program to create the same virus like in FO3) and there's plenty of stuff that points to the commonwealth being such a shithole is because of a deliberate program of destabilization. The obvious conclusion to come to is that the Instituted has deliberately released mutants and infiltrated with synths in order to prevent the formation of an NCR equivalent, which would wipe them out.

Except then you infiltrate the Institute, and it turns none of that shit was planned, the super mutants got unleashed by mistake, and they're not infiltrating with any purpose other than making better synths and seeing what happens.

There are problems, but I think this person doesn't understand that the American colonists didn't need to deal with nuclear fallout, like the thing the game is named after. The main problem is abandoned buildings and infrastructure surviving with no intervention in America when it is barely holding on as it is now.