In fairness he explicitly says he is trying to explain why it&#x27;s not popular. Not why it&#x27;s not a gold thing to learn. He days it&#x27;s a good thing to learn at the end of the article.<p>The reason he says it&#x27;s not popular is because the vast majority of people think imperatively when dealing with a problem that involves state and time. They might think functionally when trying to express an immutable law or when categorising the qualities of a horse or whatever. But when doing something that involves changing the state of the world in time and space (which is a significant part of many programs) they think imperatively. And even C will support enough of the functional stuff to do the rest (see Numerical Recipes, for example)