Anything graphical is naturally difficult to use with the keyboard only, but since you bring up CAD/CAM --- that's an example of software which is equally difficult or even impossible to use with the mouse only, especially when you want precise control over things.
My dad had a digitiser tablet for doing CAD, this big slab in front of the keyboard with a mouse like thing but instead of a ball or optics it had a crosshair made out of copper on it to precisely pin point where you were on the surface. There was an area that represented the screen and around it were all manner of UI shortcuts.
I remember it was much more accurate to use than a mouse, and better interface than having toolbars all over the display.
so did my dad for a very long time. But in recent years he (and my brother as well) switched to a normal mouse. I haven't asked him why (I should!), but I suspect that lack of support from more recent OS revisions and the hardware just being harder to find might be a reason.
I have used the digitiser a few times and it seemed much more efficient than the mouse.
Also autocad has (or at least had, last time I looked at it years ago) a very prominent prompt where to input keyboard commands (in autolisp, no less!).
Very possible. Also, with everything being already digitised today, there is less of a need of being able to precisely input points from a piece of paper.
True, I had my setup done fps style. Most of my commands were within finger reach of wasd. When i first learned the software, there were no commands set to hotkeys. It was a lot slower using menus or toolbar buttons.
