Scala projects are difficult to maintain
I had a startup that went all in on scala.  By the time we realized we chose the wrong language it was too late.Complexity is the primary issue with the scala language... when the whole goal is to have a scalable language which in itself is diametrically opposed to simplicity, your language is dead on arrival.After using Scala, Go seemed like a dream come true.We really loved the integration of OO and FP, really miss the FP awesomeness honestly... but simplicity trumps doing either of those things well.