This allows moist heat cooking to go above boiling point and therefore cook food faster. Dry heat methods. Browning of foods is a result of carmelization of sugars. This cannot be achieved in moist heat. You have to have dry heat.
Moisture then dissolves the carmelized sugar and causes brown liquid.
Another type of browning requires dry heat. It is called Maillard reaction . This reaction occurs when sugars and amino acids in carbohydrates go through a series of reactions in heating which result in browing of the surface of bread.