> there's no way a single language would suddenly progress through all layers no matter what its qualities.
Except that's exactly what languages that provide a business value do (like the ones I mentioned). Maybe not always in all layers, but they tend to fill a big, wide niche at a company very quickly.
I understand your question though, it's highly possible that the devs picked haskell for their own interest. But so far it's been a few years and the haskell "module" is dealing with the core of their business.