Clothes need space to move when spinning around so the soap can work its way into the fabric while also having the freedom to be rinsed thoroughly.
The clothes actually help each other get clean. Fabric rubbing against other fabric helps to dislodge the dirt and grime from in between the grain.
You’ll also waste time and defeat the purpose of washing the clothes because the detergent won’t properly wash away either. If that’s the case, you’ll end up having to run another cycle just to rinse the clothes.