If you want to hire the best and willing to pay that is no longer a concern
They use OCaml because it is explainable. Which it is. They use it like a non-lazy version of Haskell -- side effects are used rarely if ever. So there's no nonlocal behavior in the code, which makes it easy to reason about. And that kinda matters when a lot of money is at stake.
Incidentally, Standard Chartered has their own compiler for Haskell, without the laziness. The group is led by the guy famous for Cayenne (the first dependently typed Haskell dialect).
Most companies don't even know that these are programming languages. Also don't assume people interested in these languages are "the best". Regarding JS, this is all hearsay, but I think nowadays they hire good profiles (competitive programmers / olympiad winner / top graduates from prestigious schools), ask them hard leetcode questions, and teach them OCaml (which anybody can learn, not particularly hard. Their talent pool isn't restricted to the OCaml community, as it used to be when they were less famous, except for niche use case (compiler work and so on...)
You got the direction the wrong way around.
Ask to introduce OCaml at any company. The first thing is they're worried about is not being able to find people. To which the answer is to train them. But then they're worried some people just won't be able to learn ocaml quickly enough. To which my answer is hire people who are good enough to learn it quickly. But then they get worried those people are expensive. Ultimately it comes down to not being willing to pay.