Elixir/Erlang isn't a general purpose language. You pointed-out one reason why - scripting. Computation is another area where the language is deficient. I'd go so far as to say Elixir's failure to challenge mainstream languages for mindshare is down to to it occupying a niche - lightweight concurrency and distributed systems.
Their point was that elixir is a good language for scripting. I'm not sure if this is true but I don't see any reason it couldn't be. I don't think "distributed systems" are niche... I think every web application I've worked on fits that description, which is basically my whole career at all different kinds of companies.
