From the point of view of the majority of their users it's high end (but not these days overpriced) hardware that happens to have a reliable underpinning to a fantastic UI.

Sure, it's got some BSD underneath, but in terms of the substantive stuff, it's the fantastic UI the users care about.

Of course as an fvwm2 user for half a decare plus, I hate Aqua, but at least I'm aware there's a point there to be missed.