Even untreated diesel is often good for two or three years. I've used it myself. There is an article about a guy who successfully used 15 year old diesel after treating it with a renewer. Microbial growth can be a problem but you can treat that too. Gasoline is much more difficult to store without treatment, especially if any sunlight can reach it.
I agree and understand. But for some of the reasons you state I wouldn't build a disaster plan around the use of aged fuel.
For example: at my main office computer center, we have a generator for backup power, with enough fuel to last about four days. We have a fuel replacement plan in place there, to make sure that the tanks are not only topped off, but are pumped out and replaced if the fuel is more than four or so months old. For 1,000 or so gallons of fuel at a time this waste is not a big deal.
If it was 30,000 gallons every few months being wasted... you can bet that it would be a big deal.