Also a big reason why C++ co-routines are the way they are, is that they were originally modeled in C# async/await as per Microsoft design in C++/CX before submission to the WG21 process.

With the big difference that all those magic classes, that also exist in a similar form in .NET, do have support in Windows Concurrency Runtime, and later C++/WinRT.

However since WG21 left the runtime part as exercise for the reader, we have the current mess of C++ co-routine talks at each conference, and even so, not everyone gets them.