What you're saying is true, but I think you're overlooking the issue of severity. Just as a physical injury can heal, especially if outside care is available, there comes a point where you can't recover.

I feel I could survive a Cold-War type nuclear exchange, providing I wasn't too close to a ground zero. The same could be said for probably 90% of the land area and maybe 50% of the US population. In my house I have about two weeks of hurricane food and water, both my cars have at least 1/2 tank each of fuel, batteries for the radios and I have enough ammunition to probably defend myself against a marauder or outlaw. Assuming I'm lucky and take precautions, I could probably survive the initial exchange and maybe a month after.

But I can't grow my own food, shooting an occasional squirrel or dog is only a temporary nutritional solution, and even though I can probably get enough water (suckin' canal water agin') I would soon become totally dependent on the rest of the world. I could provide security against a lone criminal, even even several armed ones, but not against an organized gang of them. I could not depend on the authorities to provide services after the emergency. Hell, I AM the authority, and I'm not going to abandon my family and home and ride my bicycle to the Emergency Ops Center and try to keep everything else from falling apart while my neighbors are trying to break into my house. I doubt if any of my colleagues will either. In the kind of emergency you are talking about the National Guard would not report for duty to enforce martial law. We'd all be on our own. A local or regional emergency, maybe, not a nationwide one. Perhaps the resources for nationwide recovery would be there, but the organization to mobilize them would not.