At my previous job we had *ALL* of them. Each service or project you opened you could guess the date it was started because of how it was built. Rails -> Node -> Elixir -> Go -> Next.js and the frontend backbone -> ember -> react (redux -> mobx -> rxjs -> [some other random state lib] -> just context! -> recoil) -> typescript and probably by now they're already using whatever the new trend is by this morning. It is insane.
None of the companies needed any of the performance provided by this tools, in fact, they all struggle with developer productivity more than any other metric, and every time they switch to the new shiny toy, productivity takes another huge cut. But hey, people get paid anyway at the end of the month, so let's keep playing.
https://github.blog/2020-08-25-upgrading-github-to-ruby-2-7/
Erlang (and by extension Elixir) is a concurrent language. You use it when you have non-trivial concurrency challenges. When tackling the right problems, the language shines.
Implementing a simple CRUD application with Elixir is overkill, because you can make your servers stateless and delegate most of the concurrency problems to the database.