I think you were wrong. It depends on the application and platform supported. C# is the one of the top 5 but not completely out of picture. I agree Javascript is the most favorite when coming to web apps. I worked extensively in javascript ( from IE4 and Netscape Navigator) and also in C#. Both are my primary skills.  Lisk windows client was pending because of node.js unsupported features in Windows environment. The node.js depedency libraries are huge.

1) Javascript is not native in nature like C++, C#.  C# uses framework where node.js uses dependencies.
2) Speed
3) It can't handle float numbers correctly.
4) When comes to mobile development, either you need a browser wrapper like chromium to run javascript applications
5) You can't access native api without third party dependencies like node.js.
6) you can write javascript shell in c# which can execute user javascript apps. Still the developers can write in javascript.
I'm not saying C# is only the one, you have alternatives like C++, Java, Ruby, Python etc.
But when comes to native mobile development in all platforms ios, android and windows either c++ or c# using xamarin.