Here's why:

* Length and Surface Area: The small intestine is incredibly long (about 20 feet in adults) and has a massive surface area due to folds, villi, and microvilli. This intricate structure allows for maximum contact with digested food.

* Specialized Cells: The small intestine is lined with specialized cells that absorb nutrients, including carbohydrates, proteins, fats, vitamins, and minerals.

* Enzymes and Bile: Digestive enzymes from the pancreas and bile from the liver further break down food in the small intestine, making it easier to absorb.

While the stomach plays a vital role in digestion, its primary function is breaking down food and not absorbing nutrients. The large intestine mainly absorbs water and electrolytes, not the bulk of nutrients.