Comment by bhaak
The Ruby on Rails project I'm currently involved in doesn't struggle with training people, but rather with retaining them. There have been a few instances where we trained a junior developer and got them up to speed, only to lose them within a year. For small teams, this can be quite frustrating and disheartening.
This issue might be partly due to the project being in a somewhat niche and conservative industry, so there are no startup vibes. However, since they started looking for someone ready to make a longer commitment than a developer who has just started their career, things have improved. But this approach also limits the pool of available developers.
It's worth noting that we also use Elixir in this project (the chief architect is quite fanboyish about it), but we have never had any new developers come in with pre-existing knowledge of Elixir.