Not sure if you are trolling or not, but here goes.
I would choose Elixir over Ruby or Python if my service needed to high reliability or if it touched the network in any significant way. Ruby and Python suck at concurrency and are "fragile" when serving lots of connections. Clojure or Scala (seriously, no one is building a product in Racket...) would be appealing but the JVM brings its own set of headaches and even with bolt-on large-scale concurrency support the JVM languages are not significantly better at these problems.
Broadly recognized syntax? Elixir is much easier for people to read than either Clojure or Scala and is close enough to Ruby that Elixir is drawing over a lot of developers from that group.
I use Elixir because it is fun, it scales well and has high performance for the problems I am throwing at it, and it helps me develop solid and reliable solutions.
Not trolling. I used OCaml because it was "fun" and "highly-performant". Would I recommend it to my clients? No. Granted, this is almost entirely due to the POS stdlib - a problem Erlang and (by extension) Elixir do not share. However, the syntax and alternative MO are still a big sell. I'd argue that the majority of people out there doing web engineering (even the big ones) don't need it. Heck, look at Facebook using PHP.
I'm not sure what my point is - it's just not an easy sell?
The easiest sell to clients and stakeholders is reduced operational overhead, lower costs, and higher reliability. Real-world stories are coming out of 10-20x reduced server counts from Ruby and Python systems that have been replaced by Elixir. We also have stories like WhatsApp (Erlang) who supports their hundreds of million of users with a few dozen engineers. The dollar cents here make it a strong sell to stake holders, and the platform features make it a strong sell to the rest of your team and software requirements.
We have also heard stories such as LinkedIn, Netflix and Twitter migrating from different languages (such as Ruby for Twitter) to Scala. How do you think this success story of building distributed concurrent backends compare to Elixir's?
Deciding on what language to use on a new project and rewriting a large app are two different things. It's much harder to sell a rewrite than it is to sell using a different language on a greenfield project.
If you know Elixir and are confident using it, you'll understand its benefits and when best to use it. I work for a dev shop where we use Elixir for client work. Elixir is performant and you end up making the most out of your server resources. That would be great for clients who end up having huge traffic. But more important than performance, I find it easier to maintain Elixir code largely because it's a functional language. Lastly, I think Elixir's Lisp-inspired macros are a great way to write reusable libraries/modules.
In essence, I'm more productive with Elixir than I am with Ruby even though I used Ruby for much longer. I find it a more pleasant experience maintaining Elixir code than Ruby code.
Try Jane Street's Core. I hear it's a better situation.
> "highly-performant"
On one core. Erlang and Elixir will blow it away when employing more cores, naturally.
Though OCaml would probably perform similarly or better (for certain CPU-bound tasks) when running N processes to N cores. You'll need to bring your own IPC mechanism - this is probably the key BEAM value add.
> syntax and alternative MO are still a big sell
> web engineering
> it's just not an easy sell?
You sell based on productivity, performance, and correctness:
"By using this technology, you will have less bugs, which is cheaper and more productive in the long-term."
Granted, this is a very hard thing to prove, it has anecdotally been my experience with ML-derivatives.
I would choose Elixir over Ruby or Python if my service needed to high reliability or if it touched the network in any significant way. Ruby and Python suck at concurrency and are "fragile" when serving lots of connections. Clojure or Scala (seriously, no one is building a product in Racket...) would be appealing but the JVM brings its own set of headaches and even with bolt-on large-scale concurrency support the JVM languages are not significantly better at these problems.
Broadly recognized syntax? Elixir is much easier for people to read than either Clojure or Scala and is close enough to Ruby that Elixir is drawing over a lot of developers from that group.
I use Elixir because it is fun, it scales well and has high performance for the problems I am throwing at it, and it helps me develop solid and reliable solutions.