What is the reason for the cleaning step in the 5 step dishwashing process?

The first step in the dish washing process is intended to remove the food bits from the surface. This is done by scalping the surface.
The second step is intended to wash the surface needed.
The third step is intended to rinse the surface using clean water.
The fourth step is intended to sanitize the cleaned surface.
The fifth, and last, step is intended to allow the washed surface to dry.