Ruby was a little-known project before Rails came along. Without Rails, we wouldn't be having this discussion at all.

I never would have been exposed to Ruby if not for Rails (I'm a novice, self taught developer). While everyone talks about how amazing Scala and Haskell are (of which I have no doubt), I learned Ruby because Rails allowed me to build little projects (usually web apps) very easily. Now I have branched out into a bit of node.JS, some Python, and some Clojure (I like the idea of learning a Lisp), but Rails was a friendly entry point.