Why doesnt food enter the body until its absorbed into the blood?

First think of your digestive tract like a garden hose, if it worked like that you would get no nutrition.

In the real world there are things happening like chewing and saliva.

Saliva is a digestive juice almost as potent as stomach acid, it breaks down the food you chew prior to entering your stomach.

Your stomach pummels the food with digestive juices before it is allowed to enter the intestines.

Fluids are easily absorbed from your mouth as well as your entire digestive tract by capillary actions (you can get drunk from a alcohol enema).

Well this is my simple minded Idea of kinda what takes place.

Sugar, and kidneys