As to your point, I don't remember the last time I had to think about using '==' or '===' in C++. Semantics differences are huge, I don't care about curly braces and semicolons.
Except Javascript is a prototype based language and the others you mentioned are all object based....but hey they all terminate statements with ; so must be identical I guess.
Control flow, method invocations, variables, arrays, boolean logic operators, and general syntax are similar enough that you can look at the JS code and figure out what it is doing.
Where's the github for assembly line firmware code? I would be very interested in learning more about other non-web-development domains, but it seems like unless you get hired right out of school to program something like cars or satellites, you're pretty much shut out forever.
Sure, maybe the author meant "pretty much everyone [who we think will be interested in our site] knows javascipt", but that's not what they said, and I don't understand that attitude at all. It's unnecessarily exclusionary, especially when their plan is to host content in a similar way to HN.
But then I guess the downside would be fewer people contributing to your own site.
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?