Because it's artificially made hard by people who enjoy complexity for its own sake. The article is about implementing a shopping cart, as far as I can make out. Well people used to write those kinds of websites, that perfectly well enabled users to browse products, fill a basket, place the order and make a payment using nothing more than notepad.exe.

Some software is legitimately hard to write, even some websites. But this isn't an example of that. The author has been sent on a wild goose chase.