To be fair, the developers at Microsoft went to town on it as well, adopting C# for parts of Windows Blackcomb, including the File Manager, the Desktop Manager, and (some of) WinFS. It turned into a fiasco and the .NET adoption was mostly dropped, as far as I remember, when they did the "reset" and pivoted to Vista.
Because the WinDev team sabotaged, the effort, instead of doing an Android or ChromeOS with everyone roaming into the same managed direction, they made sure they pretty Windows APIs would win..
So since Vista all new APIs follow Longhorn ideas, while using COM, followed by Windows Runtime, with the caveat that tooling is just as bad as before .NET was invented, but hey they are happy fellows on their little turf.
To be fair, the developers at Microsoft went to town on it as well, adopting C# for parts of Windows Blackcomb, including the File Manager, the Desktop Manager, and (some of) WinFS. It turned into a fiasco and the .NET adoption was mostly dropped, as far as I remember, when they did the "reset" and pivoted to Vista.