Ehhh, a lot of high level languages support low-level interop. Python, Ruby, etc. It's not something you usually reach for as a user, but rather as a library author.
Of course everyone wants their language to be faster, but the interop story for Elixir/Erlang is very good, all things considered.
I love there’s a way to make apps on BEAM faster, I hate that you have to do that with non-native Erlang/Elixir language.
If only the BeamASM could be 5x faster than it is, rustler wouldn’t be needed (and come with all the downsides of NIFs).