> it doesn't exist because nobody really wants it.
Clearly not true, as there's two separate fullstack frameworks being actively developed[0][1], not mentioning the ones in the past (sails.js, meteor.js).
I think the parent comment was referring to the overall market position of RoR, and I'm saying that Node isn't likely to achieve an equivalently dominant share going forward, due at least in part to the wide variety of options available.
Ruby on Rails seems like a kneejerk response, but then again it doesn't exist because nobody really wants it, not for technical reasons.
For example, Python has all the ML/math stuff. Nothing comes to mind for Ruby.