I didn't even mention OS X in my post. For your time frame reference, OS X didn't exist in the mid 90s. But in general, we compare OS X to Windows NT 5 and 6 all the time, so what's the problem?
I was giving an example of how the operating system's architecture greatly influences its ability to perform such tasks. BeOS could do it on the same hardware that Mac OS couldn't. This was around the PPC 604 era, long before the Altivec instruction set that made the Apple G4s fast. Windows PCs couldn't do this even after the x86 had leaped past the 604's performance.
The reason is simple. BeOS was designed to efficiently use multiple processors, it was was pervasively multithreaded, and it preemptively multitasked to make sure nothing could hog the system. Sure, NT had SMP and preemptive multitasking, but it was not designed as well as BeOS for this sort of task. The MacOS at the time but could not use multiple processors well and it was not preemptively multitasked.
Of course here you also get into a bit of horses for courses. For example, I can safely say Windows NT-based products suck at real-time processing compared to the likes of VXWorks. But VXWorks has its own limitations.