Why is the digestion of starch to glucose necessary?

The substrate needed in the first step of the glycolysis in the cellular respiration is glucose. Without glucose, fructose-1-6-biphosphate can not be made. Without this critical step the much needed pyruvate can not be produced, which will halt the Krebs Cycle (due to lack of pyruvate), and the ATP production will stop. Without glucose neither aerobic or anaerobic respiration can occur which means no net ATP at all.