Earlier quoted context omitted.
For the pedagogical purposes of the book, you don't really need Jane Street Base/Core though. Plus it ignores some pretty widespread community libraries (like Lwt) and pushes its own Jane Street version, Async (which incidentally doesn't support Windows). Anyway, this has all been hashed out before.
Yes, I’m aware it’s been hashed out. I was just explaining for the benefit of people not versed in the community why Core is so popular and used in this book, which is focused directly on practical applications of the language.
Like I said, you don't need Jane Street Core for the practical application of the language. Many people who are using OCaml practically are not using JSC.