I have absolutely seen it in the wild, but at least in my case it seemed to be more a case of "People who wish they were writing Haskell, but found more commerc

I have absolutely seen it in the wild, but at least in my case it seemed to be more a case of "People who wish they were writing Haskell, but found more commercial opportunities with Scala" compared with "People who found Scala to be an improvement over Java". At the extreme of the first group you'd have people for whom it seemed like every problem was best solved with a higher-kinded-type. And while it might well have been technically (and mathematically) elegant, the rest of the team was left scratching their heads trying to understand it.