Only if "Web" for you consist of mostly static content.
For others there is an interesting thing called Web Applications.
How do you gracefully degrade a game done with all cool stuff HTML5 and friends offer?
No, I'm not talking about static content, I am talking about dynamic content, which is exactly what Rails is there for. If you only have static content you don't even need Rails, just have the web server deliver it.
I was not talking about "Web Applications" either, which, FYI, are not the same thing as dynamic content. I realize that he mentions in the post that he's mostly talking about Web Applications, but then he's just stating the obvious and the post title should be "For Web Applications, Rails is just an API".