I too adopted Scala in 2014 and was really satisfied with FP side and how it all was tied with JVM. Honestly I always felt that JVM is a nice platform with a horribly verbose “assembly” language that is Java.

Fast forward to around 2020 and I had to organize a team to build search engine in JVM. Given how hard it is to find decent Scala developer I surrendered and did this project in Kotlin. Java devs easily pick up and write sensibly FP-style even code, and builtin coroutines are cool. Even though I had to open up the internals of coroutines to get tracing to work they felt a very welcome change compared to say monadic explicit async.

So for me Kotlin is kind of watered down Scala for typical Java folks and I could tolerate it compared to perspective of writing plain Java.