They're less concerned about people writing portable code than having to implement, arguably, poor crossplatform standards (YAYS! everyone get the to enjoy the same, suboptimal experience!). So, like the above blog mentions, they have a rather neglected poll and instead, simliar to NT, want people to use "their" event monitors (kqueue,iocp,epoll). Now, iocp is quite different, and harder to support, but even then we have helpers like libevent or libuv.
I'm thinking about iokit (on the very lowest level) and the various core services that allow mac to have such fantastic apps (and happy devs).