One typical example of using a Stateful Session Bean is through a ShoppingCart example. We create a bean instance of the ShoppingCart class, then store this instance within a HttpSession. However, the same can be achieved easily with the ShoppingCart class being a normal Java class (or a stateless session bean). A request of adding a product comes in, we create a cart object, then put that cart object inside a HttpSession.
So, I don't see the point of using a stateful session bean ShoppingCart here. And in general, a stateful session bean doesn't seem to play any significant roles.