Design patterns are just a way to convey an idea. If I name something a factory, everybody knows its purpose. If I name something a prototype then people who are familiar with patterns know it will have some "clone" method. So it's a bit like UML redux. But one only need iterators if the language one uses doesn't allow you to naturally express custom iteration without requiring you to write a class or some other boilerplate.

The article demonstrates that fact pretty well.

It's also a good way to judge how practical a language is. I don't need to write iterators in a language that has generators for instance. I don't need to write factories in a language that supports closures... But then people selling all these expensive modelling tools would be out of business ...