Thanks for asking Dmitry. There are many situations where Windows full screen on a monitor is needed. OSX's way of turning off other screens when going full screen is one of the dumbest things I've ever seen, particularly in a multi monitor environment (there are 3 screens here.) I realize that's not a Parallels problem, but Parallels 11 allowed me to work around that.
I can't use "Separate Spaces" as that leaves a menu bar at the top of each screen; one of our displays is for video playback for clients, I can't have that menu.
Graphics features are minimized in Windows (no Aero, etc.) when in Coherence mode.
It's often simply "nice," and frankly very productive, to have what appears to be two separate machines (Windows and Mac) on side by side monitors and being able to share files.
As things are though this discussion may now be moot. I'm running a test setup with an upgrade to Mojave. It won't show mounted Windows drives on the Mac desktop (only the C: drive, not others.) I also can't open any Windows files in Mac applications, the app opens but the file does not show up. I can't navigate to it from the program. Windows is showing roughly 16 new Mac drives in Explorer, all inaccessible. I've tried the usual steps to rectify this, no luck. I don't want to take this thread off topic, but I doubt starting another thread will get me much support for Parallels 11 at this point.