Only reason I can think of is performance.

There are. Yes. But the previous poster seems to imply they have NEVER seen code written like that that would be improved by making it a pure function that returns a value for the caller to assign. Never? That seems unlikely to me. Unless they've only worked with really really amazing programmers. Even then it seems unlikely.

You can do that in Erlang/Elixir too, though you are passing a name/ID of the thing, not a reference to the thing itself (not in the sense of C/C++ or Rust references anyway).