Scala is too complicated. Most scala code bases I have worked on have no enforced structure, the language allows for all sorts of unconventional programming paradigms
With languages like Scala I think its a clearer necessity that someone or some small group in an organization maintains a dominance of expertise or you have different groups that are only using the same language in name or facing overhead to keep in agreement where a lot of the best developers might be basically doing ambassador work.
I would say Clojure is a big exception to that - Clojure applications tend to be more uniform than even non lisps