Jane Street wasn't all that prestigious when they started using OCaml. The way they put it is "it was easier to find great programmers in the empty set of people who know OCaml than in the huge set of other programmers" (roughly). So, on the contrary, I think it might help boring cludgy company find quality talent.
I think there is a fallacy being repeated in this thread, namely that the choice is between mainstream and weird, or between old-and-tested and new-and-shiny. No, that's not the choice. The choice is between tools and abstractions that are helpful and productive, and those that aren't. Some of the helpful and productive things are old, some are new, some are mainstream, some are niche.
I don't fully understand how someone wants to spend their career in programming and not actively seek out what is helpful and productive, rather than what currently gets the most questions on Stack Overflow or has a big pool of people who put it on their CV. It's not like all languages are equally good. It's a wasteful approach.