"Any large retailer that ran dry has a problem somewhere in inventory management or demand forecasting."
That's only two legs of a three-legged problem. The third leg is delivery. If the trucks can't get through, you still have a problem.
Delivery happens before the storm, and/or deliveries as soon as possible afterward.
Snowstorms have happened before and it's possible to model every aspect of the problem and work out solutions. There is an entire industry of guys like Doug who consult with supply chain managers on "Equipped to Keep Your Job in the event of ___". As one executive put it in our company 20 years ago in a different context "there are no surprises, just things for which you have no plan".
(when Wal-Mart shows up the day after hurricane landfall with a truck convoy of portable generators it's not because someone had a sudden brainstorm - there are contingency plans drawn up months & years before,set in motion many days ahead of time covering the generators, trucks, escort, permission to enter the aftermath area, etc. And if those generators don't get there the day after, someone probably gets to "explain" to the CEO why not)
In this case the two storms were so close that many businesses may have opted to run out of perishables rather than have the risk & expensive of trying to get stuff delivered between storms.
This is just a variation of the supply problem hospitals go through, except that a store can afford to run out off something if the cost of supply or storage is too great.