It also helps that Jane Street has like 3k employees, a good chunk of whom never touch code at all, and of those that do, a good chunk who won't be touching OCaml. Hundreds of OCaml programmers though, yes.

That may not scale for larger companies.

Also important to note, they don't require you to know OCaml when you get the job. They will teach you OCaml.

All that said, man it would be cool to work for JS (or anyone really) and write OCaml.