Typescript won over people who mainly wanted static types I think but not the functional programmers.

I think people preferring FP on the frontend are using ClojureScript, PureScript and ReasonML now. Eg here's Dark's interesting story going to ReasonML via automatic translation: https://blog.darklang.com/philip2-an-elm-to-reasonml-compile...

(ClojureScript ecosystem was always much bigger in any case I think)