The reason why Enum always returns a list is because there are many Enumerable.t types, which invalidate their own constraints when mapped, like ranges or various streamed enumerables. E.g. what would Enum.map(1..10, & &1 * 10) return.
As alternative in elixir you have the Collectable protocol as well as all the erlang/datatype specific functions like the already mentioned Map.new.
