I am not that sure. He's starting to learn how to use an old Macintosh computer that we have. The chance to interact with other children is the benefit of preschool in a nutshell but it is far more than what those few words say. You are so wise to pursue more information when you feel that the obvious may not be all there is to know. Interacting with other children means learning how to wait, how to take turns, and how to listen.
Young children learn social skills when they interact with other children.
These social skills are critical to a developing personality and I would not dismiss them lightly. The play that takes place with water, sand, and containers form the foundation for understanding some basic math concepts. Watching other children pursue a challenging task is also helpful. The presence of other children and a wide variety of materials are two big reasons why a preschool is a good thing. I believe preschool is beneficial and can do many things that will help children be successful when formal school begins.