That's true. I'm only addressing the proposed scenario - projected 90% die-off following a total collapse of modern civilization. At this point you'll have to deal with large amount of desperate, starving people radiating away from cities and towards any and all known farms, warehouses, and food/water sources. But having a food stash is a really good idea anyway, because if a disruption is only temporary (say, a week or a month), it may be a difference between living and dying (or not wanting to live with yourself anymore).