I think the reason some may be stocking up on non-perishables is because much of our economy has become Just-In-Time manufacturing and Reduced Inventory. If 1/3 of Americans become sick, and another 1/3+ are working from home, laid off, furloughed, etc. that doesn't leave very many people to make/compile the resources, deliver the products, stock the shelves, and manage the money/security. Also, if the utilities experience issues who will be there to make sure they get fixed and are running smoothly again? Lastly, are you really going to want to go out and about while this is happening?
An argument can be made that if they're wrong it's no big deal; just some more non-perishables that they won't have to buy for months. However, if they're right....
We don't really know how bad this can get. Transmission is exponential. It could be slow for awhile and then explode. It's really only been a few weeks that cities have been shut down. People will start to get pretty restless when they run out of food, and then they'll be out and about, spreading it again.
I think it will be less of a disaster then some predict, but getting prepared is probably sound advice.
