High throughput. As I've said elsewhere, realtime != high throughput. Just deterministic throughput. Users of these systems are willing to use slightly overpowered hardware if it means hitting processing deadlines.
For the desktop, most users care about responsiveness, not throughput. That high throughput Linux kernel makes it utterly craptastic for professional audio usage, with insane amounts of latency. Of course, that has more to do with ALSA being a steaming pile than the kernel in general, but it's one example that shows throughput isn't the only thing that matters /especially/ on the desktop.
