I don't really agree. I think people make a lot of assumptions on the "losing" side of the interview table. If you don't get the position and feel like you aced the interview, you search for some justification that has nothing to do with your performance. The fact is, there are 10 people vying for a single position. All else equal, If we use angular, I'll take the angular person over the jQuery person (emphasis on all else equal). That person will likely chalk it up to jQuery instead of the simple fact that there was an equally qualified candidate with a more specific skill set.