All manufacturers of dishwashers claim that for proper drying rinse aid must be used. A rinse aid’s only purpose is to aid in drying and reducing waterspots. It does this by changing the surface tension of water.
When a drop of water is put on a smooth surface it beads up. It is surface tension that holds that bead and it is the natural state of water. Just a drop of rinse aid changes the surface tension of a lot of water and makes it flow off objects easier. RINSE AID IS DISPENSED IN THE RINSE CYCLE OF A DISHWASHER. When a glass from a dishwasher that uses rinse aid is filled with water, bubbles rise to the top and fall back down. It is not detergent that causes those bubbles - it is rinse aid.
PEOPLE ARE MADE OF 75 % WATER! It is not a good idea for us and especially children to drink anything that changes the surface tension of water.
If you’re not satisfied with how your dishwasher dries without using rinse aid you can pop the door ajar (1″) up to 30 minutes after the “dry” cycle. This is called “flash” drying and provides venting for moist air to escape from the tub. Do not leave the door open all the way as that is an accident waiting to happen.
A few more waterspots may be noticed if no rinse aid is used but one must weigh the practicality of ingesting a chemical against having spotless dishes.