Dishwasher

What's the point of a dishwasher? It's to wash dirty dishes so that we don't have to wash the dishes ourselves. I have known many people to rinse off their plates before they put it in the dishwasher. Doesn't that defeat the purpose of the dishwasher? Its job is to wash dishes! I'm not going to waste my time rinsing off whatever before I put it in a machine that does that for me. Sometimes the food gets hard and congeals on the plate. I understand that. However, I'll deal with that if it sticks after I run the dishwasher. People who rinse before putting plates in the dishwasher are weird, haha!