Good question. Their libraries are robust and certainly useful if you want to develop real applications. I'm not sure but I'd say no because I think they add an extra level of complexity of a newbie. They are also quite opinionated which some people may dislike.

I talked about "confusion" because I suppose a newbie may quickly be confronted with this question, for intance if they want to follow "Real World OCaml" which is based on Jane Street libraries.

The tooling around OCaml has really improved a lot these last few years (opam, dune, core/async, merlin, ppx...). The downside is that it raises the bar for newcomers.