Since applications do all their rendering via the GPU these days, desktop multi-tasking requires reasonably time-sliced access to the GPU. GPUs have proper memory protection these days (GPU-side page tables for each process). That's big progress over 10 years ago.
True. But it's still far away from a unified approach you'd expect (as someone outside the field) in a modern OS. After all, one of the jobs of an OS is to abstract away access to underlying hardware as much as possible. Until we get some improvements here, my hopes are not very high for the FPGA domain.