Can A Cheeseburger Exist Outside A Post-Agrarian Society?

A post arguing that this is a Question To Which the Answer is No has been cropping up on my Facebook feed lately and now I see that Andrew Sullivan has linked to it as well. As Waldo Jaquiath puts it, the cheeseburger was until relatively recently an impractical concoction. Not impossible, perhaps, but one requiring many actors and moving parts:

This past summer, revisiting the idea [of making a cheeseburger “from scratch”], I realized yet again that I was insufficiently ambitious. I’d really need to plant and harvest the wheat [for the bun], raise a cow to produce the milk for the butter, raise another cow to slaughter for its rennet to make the cheese, and personally slaughter and process the cow or sheep. At this point I was thinking that this might all add up to an interesting book, and started to consider seriously the undertaking. Further reflection revealed that it’s quite impractical—nearly impossible—to make a cheeseburger from scratch.