Well that was a strategy indeed but it can only go so far, additionally the same logistics apply to the food you place in the cache, you have to transport it there, the meat of the original article was, that really you are constrained in your movement by the terrains agricultural output, in high production terrain, your population and the enemies population as well will stockpile food for themselves that the army can draw upon, in places where the terrain is not suitable for high intensity agriculture the food available is much less and an army would quickly find itself exhausting all the stockpiles, in a matter of weeks, armies eat a lot of food.