It's possible because the number of programmers that have been exposed to Erlang and Elixir is a very small fraction of the total. Besides, many programmers go through their whole career in a single eco-system (.NET, Java, C, C++, COBOL, PHP etc).
Hmm, I was dabbling with Elixir for quite some time now, but never considered myself proficient enough for applying to Elixir jobs. May be worth a try.