Using Scala and then complaining about unnecessary complexity is a bit much. Like, if you made the technologically brave decision to use a niche language like Scala that isn't just a slightly better Java like Kotlin then you'd better expect to accommodate the inexperienced developers by training them, possibly via pair programming, instead of constricting the experienced developers.

Post was in 2016 when Scala was almost required to use certain big data tools (apache spark, etc), the alternative being python and its limitations.