If you check out the first post, you'll see that C# is fairly low in the overall listing for languages. It has been over taken by Go for example. Even if all of the C# jobs were MVC, it wouldn't be enough to compete with any of the JS frameworks.

This analysis isn't that far off of some of the other trends you'll see from resources such as Gartner. Windows and .Net have taken a beating recently due to the growth in the cloud sector of IT.

In addition to the .net core push seems a likely candidate to unify things (xamarin, .net core in Linux, etc...)

I know it can, just as Java can. It's not very common, though. Particularly in the up-and-coming companies. I'm not surprised that .NET and Java get lost in the noise created by all the JavaScript/Ruby/Python.