I think he just wants to separate the presentation from the logic, which might be good when you don't trust designers re-jiggling things, and you want clean code. Plus, if you're working with a lot of AJAX, it's nice to be able to reproduce the presentation on the server the same way you do it on the client. I suppose keeping the two in sync can be difficult, which is why you probably would only want to render on the server on the initial page request.