Comment by jraph

HTML is perfectly able to do what it was designed for: mark up documents.

There still needs to be something like HTML even when you have PHP: PHP is something you run on the server and it still needs to output something to the client in some format, and HTML is adequate for this.

The heck we are doing with HTML is taking it for building client apps. But even then, you now have UI toolkits that mimic this model: QML, whatever XML format Android has to design UIs, etc.