Maybe it's because nothing related to files is showing up. For example, Java has packages, classes, protocols (interfaces), methods, and documentation. All of

Maybe it's because nothing related to files is showing up. For example, Java has packages, classes, protocols (interfaces), methods, and documentation. All of these are visualized in a Java IDE. But Java _also_ has folders and files, so these need to be visualized, as well. At least in Java there's a pretty clear mapping from packages and classes to folders and files. In PHP, the mapping is not so clear. Edit: I'm not saying I agree with the author, I'm just pointing out one aspect.