Highlighting an important distinction Chris makes: there's a huge difference between needing to learn to read/understand the basic syntax of a language and needing to learn to write it.

When writing Elixir, yes, you'll be exposed to Erlang syntax/docs sooner or later. But you're not writing Erlang, so you never need to learn how to:

  - Compile more than a couple lines of Erlang into a function
  - Create an Erlang module/file
  - Learn Erlang's build tooling
  - Cold recall its syntax

Creating something functional from scratch in a language is 100x (1000x?) more challenging than learning how to roughly read it.

I've been programming full-time in Elixir for a couple years. All told, I think I spent 3-5 hours one afternoon learning the basics of Erlang's syntax so I could better read the docs. Haven't had to think about it consciously since.