On the other hand the asynchronous parts of the Socket API was modeled after the Windows kernel, which has true support for asynchronous sockets.
That's one reason why the Mono implementation was always suboptimal, because implementing that API on top of poll, epoll, kqueue and the like is not really straightforward. It's also the reason for why the attempts to build alternative web servers are using bindings straight to libevent, bypassing the socket API.
The original plan was indeed for .NET to be portable to non-Windows platforms, but Windows-specific details have leaked in nonetheless.
That's one reason why the Mono implementation was always suboptimal, because implementing that API on top of poll, epoll, kqueue and the like is not really straightforward. It's also the reason for why the attempts to build alternative web servers are using bindings straight to libevent, bypassing the socket API.
The original plan was indeed for .NET to be portable to non-Windows platforms, but Windows-specific details have leaked in nonetheless.