The actual design and standard are designed to be multiplatform. You can see it in a lot APIs, like Environment.NewLine -- not needed if you only target Windows

The actual design and standard are designed to be multiplatform. You can see it in a lot APIs, like Environment.NewLine -- not needed if you only target Windows. MS released Rotor as a proof of concept. It's just an argument over implementations, which were admittedly lacking. And the standard parts are smaller than the whole .net bits MS shipped.