I agree that Erlang has some benefits in the early stage of development or with smaller projects, but beyond that you anyway will need devops and this argument no longer holds. One example I have is whatsapp being started in Erlang by a few engineers and it was a huge success from engineering point of view, but later rewritten (I think in C++) anyways. They had their reasons but it's clear that something in Erlang was not satisfactory and fault-tolerance with distributed nature was not enough to stop it.