[Pannoniae]

The sad answer is that it's because it's not familiar to most programmers. The quality of the tools sadly has barely any bearing on their adoption.

It's just too different and too advanced for the average programmer to use. There is no surprise that we have languages like Go now - explicitly familiar, explicitly dumb.

Elixir does not have familiar C-like syntax or the usual OO-ish programming model, and its (btw fantastic) approach to concurrency is also very strange to people coming from popular languages.