Except that C# is a first class citizen on the platform, not a wannabe replacement for the platform's main language.

This already makes a lot of difference in the tooling that one gets from the platform owner.

Another thing is from the point of view of customers.

With C# I can get all the goodies on customer projects.

With Scala, I can only play with it at home and try to be happy with Java 8 on customer projects.