People should be more concerned with fundamental skills IMHO. I don't think there are Ruby and Javascript programmers. You're either a programmer or you're not. What language/framework is just a means to an end.
Yep. Here and on reddit people are happy to say "we hire for programming skill, not framework or language knowledge!" and they may be right.
However, almost every time I have been rejected or offered a job and given a reason has been for a lack of domain knowledge (or in the latter case, possession of that knowledge!) of a particular framework or language.
True, but as a programmer, I believe you have to at some point start filtering out jobs that are hiring for <insert technology>. That doesn't leave many jobs and one has to be willing to look long and hard for them, but when you find them, you'll be more satisfied.