But there is a very compelling reason to use TypeScript. There isn't one for C#.
(And, oh man, that batteries included battle tested framework is a stinky pile of trash. The language itself is ok, but the framework uses every misguided trend somebody at MS thought as cool, has no documentation of them, and implements half of them in some way that only that person thought about. There is a passable "web framework" inside it, but you have to ignore the MS recommendations and know what tons of pieces to discard, also, it's not very batteries included, because the batteries are almost all poisonous.)
This is kinda totally off. You could say that about Spring and Pivotal/Tanzu/VMware or even Quarkus and Red Hat, or just IBM. In my experience though those words apply best to much of the Python and Rust landscape. You could say much more about the Node landscape. But .NET and ASP? Really? Could you substantiate?
I find the opposite to be the case in all honesty.
I've never used C# or dotnet core but I know from word of mouth that it is a relatively well put together framework of tools for doing a lot of the things organizations with a lot of backend services to write might need. Many of those orgs are already very locked in with Microsoft, so the greater support by the open source community that comes with typescript is mostly irrelevant. Whatever the officially supported version of something is is what you will be required to use, and the typescript ecosystem provides very little if you want some big company to declare one particular thing to be the blessed solution.
(And, oh man, that batteries included battle tested framework is a stinky pile of trash. The language itself is ok, but the framework uses every misguided trend somebody at MS thought as cool, has no documentation of them, and implements half of them in some way that only that person thought about. There is a passable "web framework" inside it, but you have to ignore the MS recommendations and know what tons of pieces to discard, also, it's not very batteries included, because the batteries are almost all poisonous.)