I'm not sure it's inefficient. It gives you the knowledge what is and isn't possible and also the semantics of what you actually do, all things you need to have later anyway. Relying only on examples is a great way to miss unintended side-effects or other consequences.
The first part of that line is "If you want an example...". If you want to learn about more advanced usage of some function, then you don't want an example, and that line doesn't apply to you.
I'm not sure it's inefficient. It gives you the knowledge what is and isn't possible and also the semantics of what you actually do, all things you need to have later anyway. Relying only on examples is a great way to miss unintended side-effects or other consequences.