Have you ever tried to install and setup PHP on a fresh server? It's almost as painful as writing code in PHP.
The article is talking about managed hosting, were that might still be true (Admins are incredibly conservative and stubborn individuals).
But for everything else? PHP doesn't work 'out of the box'. It's due to the work of a poor admin somewhere that you can just upload your crap and it runs.
In contrast, I can install and setup a complete Ruby server in about 15 minutes.