I have never really grokked Ruby on Rails and I passionately hate all the frameworks that try to adapt it to some other language.

That said, I suspect that Ruby on Rails itself occupies kind of a special space where the magic is acceptable because people who write Ruby are used to having very very sharp tools and have learned to wield them carefully. Give that magic to a PHP or Java programmer and there is immediately gallons of blood on the floor.

(says former Rubyist who was put off by the RoR stuff because I'm apparently more of a Haskeller at heart.)