It's not about it being hard, it's about this mentality that software == web development. There is so (
so) much more software running different applications. I'm not saying that the developers of this site actually think that the world literally runs on JS, but I found that sentence amusing and somewhat ignorant.
I work in systems. I don't really know JS. I do know C, C++, C#, Haskell, various dialects of Lisp, Python, and Ruby however. Why would I subject myself to learning JS unless I absolutely needed to?