Certainly, but all of these things are nascent or not adopted with sufficient volume to assert a de facto standard. In that sense I think "JS is the 'only' thin

Certainly, but all of these things are nascent or not adopted with sufficient volume to assert a de facto standard. In that sense I think "JS is the 'only' thing available for the front-end" isn't unfair. As regards the backend, I don't think it's justifiable that anybody would actually choose JavaScript. There are far better, more stable options. The only reasons, as I see it, to choose JS for the backend are to cheap out on developer spend or to follow a fad. "Isomorphic development" falls in the one or both of these. Excellent, highly (Google) scalable products have been produced without that for two decades now. Asserting it is just, in my opinion, a way to mask one or both of the other reasons.