Yeah .. but there is one aspect in this argumentation: C# is everywhere a reasonable contender. So while you rarely get a dominant position (Unity and Backends) you get a lot of second places (Apps, Desktop, ...) which complement your full stack experience in an awesome language. And this is different to other languages: Python/Go: no-show in apps; JavaScript: no-show in data science; Swift: no-show in backends (thanks IBM).
From a management perspective, this is not bad. You get movable team members. In my company we have moved people from WinForms app, to cloud deployed micro-portals and then to a Apple/Android App (all different solutions .. not a migration). C# play a big role in that.
I think this is again a dark-matter-developer / line-of-business situation.