Not all web developers are "plumbers". If you are working on websites with heavy traffic, then you need to use complex algorithms to scale. That needs someone who is comfortable with algorithms, and that needs a quite lot of thought. The author describes simple CRUD websites and then equates all of web development to trivial tasks like that. Even scaling simple CRUD needs a lot skills, intelligence and ingenuity. And…
I imagine plumbing the Burj Khalifa needs a different and more advanced set of skills than plumbing a prefab home.