I'm not familiar with RoR, but that explicit version is hard to read. However, I think the problem with implicitness is that when it becomes wide-spread, nobody can read the code with ease (i.e. everyone made their own implicit code, and it comes together poorly). I see nothing wrong with a little bit of magic, especially if it is something you use often.

Side note: the author has a short paragraph about "simple/easy" and "complicated/hard" products, which doesn't ring true with me. I would think most people would say their software product is "complicated, but easy to use".