In most jobs you will not get a foot in the door if all you claim to know is fundamentals. If you do not know the languages or frameworks they work in the interview is over as they are not going to spend the time training you. They want you to get in and be effective as soon as possible, not pay for your on the job training.
Personally I have found that this is relevant only for front end work. For the backend you just need rudimentary knowledge of a framework/language to get your foot in the door, then the actual testing is language agnostic.
