I don't really really agree with the idea of [New Framework X] job boards either. Languages, I get: if you know Language Y, you can probably pick up Framework X in a few days, and by the second week no one will know you came in without knowing it. Honestly, extend the timeline by another week or so and you can apply the same to languages (with talented devs at least).
Personally, I don't consider myself an Angular developer - I'm a developer (a "full-stack developer" if I had to qualify the term somehow). I can pick up any Javascript framework in a reasonably short amount of time, because I have a lot of experience with the language.
Furthermore, who's to say you'll still be using Framework X a year from now? Your needs will change, and all of a sudden the premium you paid for that specialized talent is money wasted. Just hire talented developers - they'll learn whatever stack you throw at them, every time.