Yes. The more different languages (and frameworks) someone has to know, the harder it is to hire them. If you hire people who only know the language of one small part of your system, they can't help out on other parts during emergencies and there will be difficulties adding new parts (which language do you use, or which existing part do you steal developers from). If you hire people who know one language and train them in the rest, the more languages there are the more that training will cost.
And it's rather a good thing, no? I mean, for me, as a developer who happens to know at least a dozen of languages quite well and has a basic grasp on a dozen more, I like it that way. Namely, I like being a harder to find good with limited supply, this means that I will be paid more.
Otherwise what would be the point of learning all these languages, frameworks, libs and environments? Of course the learning experience can "make you a better developer", but is it supposed to be only that?
