Apple actually did put some resources behind it, the toolchain is reasonably pleasant to use outside macOS and Xcode, they have people building an ecosystem in the Swift Server Workgroup, and arguably some recent language design decisions don't seem to be purely motivated by desktop/mobile usage.

But in the end I can't help but feel Swift has become an absolute beast of a multi-paradigm language with even worse compile times than Rust or C++ for dubious ergonomics gains.

> Just like, I suppose, C#

Have you actually used .NET on Linux/macOS? I have (both at home and work) and there isn't anything that made me think it was neglected on those platforms. Everything just works™