I hope all the stores don't close because I don't have twenty years worth of canned foods in the basement.
Google "Just-in-time inventory".
It is easy for even a poor man to decide to stock up on green olives, or spaghetti O's, and clear off the whole shelf. Everyone else in that part of town doesn't get any of those foods for the next week, until their next shopping day.
It's a ridiculous power trip, if you think about it. When you consider how easy it is, it shows how ludicrous our food distribution system is.
All it takes is $30 or $40 in grocery money. Even those on Food Stamps could do it. So it doesn't take a lot of financial power to decide "no one else gets canned chicken today."
Imagine if there were a disaster and EVERYONE wanted to buy food -- those shelves would be cleared off post-haste. And if there was any real disruption (credit collapse, riots, martial law, nuclear bombs, dirty bombs, EMP shockwave, asteroid impact, you name it) the trucks wouldn't physically be able to get through and resupply the central warehouses and all the stores that depend on those warehouses.
You would have whatever food is in your home, plus what you can produce in your home/backyard. Nothing more.
You will find that few things have no downside, and few things have no upside. Everything is package deal of upsides and downsides. Everything comes with a price.The improvements to agriculture that permit most of us to ignore growing food is the same thing that makes us so vulnerable to starvation if there is any disruption in the system. So you see, there is a downside.
Nothing "good" comes for free in this life. Everything comes with a price.