You're absolutely right that the end of the article is a hair's breadth away from monads. In fact, monads were secretly used throughout the article in the form

You're absolutely right that the end of the article is a hair's breadth away from monads. In fact, monads were secretly used throughout the article in the form of the comprehension notation (which desugars to the List monad). There's also a tight connection between continuation-passing style, continuations and monads. More on that in a future post...