Why is the Command Pattern convenient in Object-Oriented Design?

I don't understand why a Command pattern is convenient in object-oriented design.

Instead of using, e.g. the Command Switch which has a reference to the Lamp class, can't I just create a Switchable abstract class and invoke its methods?

In this way I'm decoupling the invoker and receiver anyway, and I don't have to create a Command object for each receiver class.