It's mostly C++ or Java (& other JVM languages) in high class finance, some python and verilog for their niches. The article is about the odd one out firm that has its own rather unique stack. It essentially says so at the end - "[you] become less employable anywhere else".

Seems a little biased since they don’t even talk about its advantages. AFAIK not many companies use OCaml in practice but it is used quite a bit in academia in Europe.

That said (I may be biased as well) I was taught OCaml in uni and enjoyed its succinctness and expressiveness.

Meh. Languages are a toolbox. Right screwdriver for the right job.