But! you're quite right. Elixir is focusing on the web application type things that Erlang and the community around it has never much addressed. There's enough interoperability from Elixir to Erlang that you could probably say the ecosystem as a whole is addressing the problem if you squint hard enough.
Side comment, it's been interesting to see Elixir grow since 2013. A lot of folks learn Elixir and then Erlang but I think it's less common to learn Erlang and then learn Elixir. It's led to an interesting situation where Elixir has had to bootstrap knowledge about OTP on its own terms without a large pool of domain experts sitting around. The asymmetry in knowledge--knowing Erlang does not imply knowing Elixir but knowing Elixir implies knowing Erlang--also makes me wonder how the squinting assumption above will shake out long-term. ¯\_(シ)_/¯