That still seems backwards. Hire developers. Use a language those developers are comfortable with. Don't choose a language then hire developers for it.
In any case, I'm not sure that many (any?) product needs could dictate choice of language in the vast majority of cases. Yes, if you need to do a ton of realtime stuff then maybe think about Node etc., but most people want the same standard stuff.
"hire developers, use a language those developers are comfortable with."
So you can use that method when hiring the first developer.
When it's time to hire the second developer, are you looking for only developers that are comfortable with the same languages as the first developer? If so, you are hiring developers based on language, and no longer following your advice. If not.... then you get a bunch of developers comfortable with different languages, and now what?
Often the answer might be "good developers can learn to be effective at any language." Which while on the whole (if not always) true, nevertheless only sometimes works for an enterprise (sometimes you don't have time to wait for them to learn it). But even so, now that turns into different advice: Hire your first developer, have her use a language she's comfortable with, then hire subsequent developers that either already know that language or are capable of learning it, and have them learn it. Which doesn't sound quite so obvious as your original advice, although it's not neccesarily an unreasonable approach.
So use what you are comfortable with - as long as it's not something that's so completely obscure that no one else knows it. If you just chase popularity, you're also probably likely chasing mediocrity. On the other hand, no, Visual Object Forth ++ from Borland is probably not the best thing to build a web site with.
In any case, I'm not sure that many (any?) product needs could dictate choice of language in the vast majority of cases. Yes, if you need to do a ton of realtime stuff then maybe think about Node etc., but most people want the same standard stuff.