OCaml "writing a first-rate concurrency-friendly runtime would require massive investment". Except it's already being done in OCaml 4.03 [1]. I still don't think this is actually a problem, since in many cases (NUMA, distributed systems) it's better to use other approaches. If the article is serious about safety, then it wouldn't encourage people to use threads with shared memory.

[1] https://sympa.inria.fr/sympa/arc/caml-list/2015-05/msg00034....