What actually happened was that I was immediately productive.
Without having to credentialize in the code, I was able to stub out new features and push an update. An infrequent experience for me in other languages. I had only a figment of an idea of the code I had to write, but I got started and the compiler helped me the rest of the way.
I still don't understand how to confidently organize an Elm app. But that describes my relationship with every front-end Javascript framework as well. I regularly choose poorly between component vs upstream state in React. But what I can do is refactor Elm code at a level that would be downright expensive in Javascript.
As far as the sour graping going on in some nooks of the Elm ecosystem, I'm reminded of this post by Rich Hickey: https://www.reddit.com/r/Clojure/comments/73yznc/on_whose_au...
Recently a new dev joined the front-end team. He had js background and no previous functional programming experience. In less than one month he was already shipping production code with confidence on our ~40kloc app. That goes to say that 1) I don't think lack of Elm programmers is a problem if the company is willing to train its employees and 2) I'm sure the front-end lead and the new dev would have a much harder time if we were using javascript.
Surely this is our experience. YMMV.