Yep; Darwin doesn't do raw syscalls, the BSDs don't (OpenBSD going so far as to block anything but libc from making syscalls, as a security feature), illumos doesn't... actually the only OS I can think of off-hand where applications regularly use syscalls is DOS, and even then it looks more like a side-effect of x86 architecture and the constraints that it was developed under. Go hit this particularly hard, having mostly grown up on Linux and then finding out the hard way that using libc isn't really optional on other systems.
On well designed systems (and I will count Windows in that group), libc is optional and syscalls are decoupled into another library. After all (unlike what some BSDs think) not everything is C, and forcing everyone to use the libc abstractions isn't very nice.
