That said, from reading the article you forgot to mention Hex, the package manager.
I learned to love Erlang some time ago and its various quirks are mostly invisible to me, as I generally know them well and am working around them reflexively. However, I recognize that for people who don't know Erlang yet, Elixir provides a much easier path to obtaining full power of Erlang VM and ecosystem. It can also benefit more experienced erlangers, as it improves some Erlang features and then adds some totally new ones.
Elixir is a language which makes Erlang better suited to high-level, glue-like scripting purposes, while still providing full access to things Erlang does exceptionally well. In a way it's an effort to make Erlang reach outside of its specific niche by making many things traditionally hard or unpopular in Erlang easy to do in Elixir.
In short, if you're a serious programmer who works on anything that has a server or is related to network in some way (which includes all web apps, most mobile apps backends, all IM software, many different services like Dropbox and many more) - you owe it to yourself to try Elixir out. Now that the "awkward syntax" and many (admittedly) irritating quirks of Erlang are gone and you're left with just the good parts you have really no reason not to learn and use it.
I think the reason for Erlang and Elixir's increase in adoption is that a lot of modern day Web applications have these same needs. Don't you want your web application or mobile app to handle failure in a way that doesn't bring the entire system down, and be scaled across several nodes easily?
The point about a lot of quality applications being in Erlang is well taken, though the interop is effortless.