If you have JavaScript, "technically" HTML, CSS, XML, and JSON are unnecessary. You can write programs to print and layout text (that's essentially what a PDF

If you have JavaScript, "technically" HTML, CSS, XML, and JSON are unnecessary. You can write programs to print and layout text (that's essentially what a PDF file is), and programs can emit and compute data as well. Kay specifically calls out HTML as a "step backward" for this reason (although he is simply wrong as I've said). He wants a web based entirely on executable code. Yes, it sounds dumb prima facie but that's what he has said consistently over a long period of time.