The Workspaces replicant has been embedded beside my Deskbar since BeOS, so about 25 years now. I use it daily, every time I need to change between 4 workspaces whenever I have the hand on the mouse. If not, I use CRTL+ALT+CursorLeft/Right.
Very often I use the replicant to drag a window over to/from another workspace.
I never had more than one monitor at home. The past ~15 years that was the panel of a notebook.
BTW most Linux desktops have virtual workspaces built in. MacOS has them, even if they are a little trickier to work with. It’s only Windows that resists them.
To answer your question; I am using this functionality all the time. But I mostly don’t use the workspaces applet, only having it as an indicator. I usually use alt-F(1-4) for 4 virtual desktops. Sometimes more but usually 4 is enough
I belong to the opposite faction, I almost never use them even on MacOS where I prefer Mission Control (or the good old Exposé).
Actually, I wish we had something similar for Haiku because the workspace concept does not fit my workflow.
Windows has supported creating and switching between virtual desktops since NT 3.51 (*actually from NT 3.5) and that predates BeOS. The API (CreateDesktop, OpenDesktop, SwitchDesktop) was fully functional but it was just not exposed to the user via the OS interface. There were a few apps that allowed to utilize the functionality, and I remember using one of those on NT 4 and 2000 (that was before Sysinternals released the Desktops tool). But the API does have limitations as it was designed with security in mind, and not for the great UX (who would expect great UX from Microsoft anyway?), the biggest of which is the lack of ability to move windows across desktops. That’s why in the Windows 10 virtual desktops feature, no new desktop objects are ever created, and the OS just manipulates the visibility of windows.