I'd wager Twitter switched to Scala instead of Elixir because it existed when they were moving away from Ruby and Elixir didn't. Maybe they still would have if

I'd wager Twitter switched to Scala instead of Elixir because it existed when they were moving away from Ruby and Elixir didn't. Maybe they still would have if Elixir had existed, but it didn't so we can't know. And Elixir is not "basically Ruby on Erlang". It adopts some Ruby stylings and Ruby's metaprogramming habits, but the language and underlying libraries are quite a bit different. If for no other reason than Elixir is not an OO language and Ruby is (and heavily depends on its OO model for many things). "trivial" is probably a word most of us need to excise from our vocabularies, translating Ruby -> Elixir may not be the hardest thing in the world, but it's not trivial.