Kotlin too. There's even a super nice wrapper over spring-data-jpa [1] so you can do LINQ-to-Entities-esque query building where JPQL queries either aren't staticly-typed enough for you or you need dynamic query generation.

[1] https://github.com/consoleau/kotlin-jpa-specification-dsl

Sometimes the "so much more" is the issue with Scala, but yeah, Scala is a great way to make you say "man, I wish I had _" in every other language you use.

Every time I look at Scala, the version has changed and the entire world needs to be rebuilt.

> Is it just cross-platform compatibility so that you can develop your C# application for Linux?

C# runs just fine on Linux, using .Net Core.