Because sometimes you're stuck to that small intersection where only a particular OS is supported by a particular technology. Case in point: CUDA. There's no su

Because sometimes you're stuck to that small intersection where only a particular OS is supported by a particular technology. Case in point: CUDA. There's no support for CUDA for OSs other than Windows and Linux. And there's no support for ZFS in whatever form on Windows. If you want to do GPU computing using programs written in CUDA and keep the data on ZFS then you're essentially stuck to Linux + zfsonlinux and you have to deal with it.