It was Apple's offering only during OS X, and only because its BSD underpinnings. If Apple had chosen to build OS X on a homegrown kernel, Apple wouldn't have been appealing to the skilled.
I also don't understand your counterfactual. Apple didn't build OS X from scratch, they took NeXT's OS and ported it to Mac hardware and tweaked it. The result was something both powerful and easy to use. Making UNIX easy to use is not a trivial accomplishment! Yes, if Apple had done something completely different for their next-generation OS then maybe they would have ended up with something worse. But they didn't.