And the reason this is more prevalent on QNX is that it's a microkernel based platform. Here, in Linux, there's the debate what should be allowed into the kerne

And the reason this is more prevalent on QNX is that it's a microkernel based platform. Here, in Linux, there's the debate what should be allowed into the kernel, whereas that question is pretty much never asked for QNX. You also don't get discussions about circumventing the kernel network stack to avoid context switches, to name a prominent example. Microkernels also lend themselves better to multikernel designs where you aim to make better use of all the available cpu cores by reducing sharing.