Appreciate the comments guys, you may very well be right! However, I suppose it could come down to something like this, for example - one may have a project which has Angular embedded deep within it. You want to hire an Angular dev - someone who knows it inside out, not just a "front end JS dev" who can possibly pick it up - needs may change, but for said project you need an Angular dev. Or perhaps the type of person that loves Angular and the way they think is who you are trying to hire.
I think as well that something like Angular which seems to be going mental at the moment is an indication of a change of thinking for doing front end work, so even though frameworks come and go, maybe the desire to hire an Angular dev is more about hiring someone who is embracing this change of thinking.
I'm sure there are lots of reasons for and against but time will tell if a) employers actually get candidates from this board and b) do developers find interesting jobs from this board.