In my experience, Elixir and Phoenix are both so straight forward you don't really need to rely on third-party libraries as much as you do in Rails. Some of the things you'd normally reach for a gem to accomplish is just built into Elixir itself (e.g., you don't need anything like Resque or Sidekiq because Elixir processes can do all of that and more for you).
The lack of magic is nice too. For example, it's easy to add a new custom Plug (that you wrote yourself) to your pipeline without resorting to third-party libraries to help you navigate all the magic and boilerplate you'd otherwise have to deal in other frameworks.
The lack of magic is nice too. For example, it's easy to add a new custom Plug (that you wrote yourself) to your pipeline without resorting to third-party libraries to help you navigate all the magic and boilerplate you'd otherwise have to deal in other frameworks.