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.

That's a graphics tablet/digitizer and a puck.

http://www.brisk.org.uk/gt1212b/index.html

Crazy high res and absolute rather than relative which makes them very useful for some applications.

Yep, that one and another less colourful model.

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!).

maybe current breed of optical/laser mice are just really good enough.

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.

A drawing tablet is better than a literal mouse. They are pretty cheap, have better ergonomics, and you can use them proficiently pretty much instantly.

For you, yes. I (and a lot of other people) have a disorder that makes my hands shakes when the muscles are tense [0]. This means that the only way I can interact precisely is with my arm laying down on the desk and only the fingers moving the mouse. This is just one example of a wide variety of problems/annoyances. To everyone out there design user interfaces: please remember that people are not either perfectly fine or with disabilities in a black&white fashion, there is a lot of grey in between.

[0] https://en.wikipedia.org/wiki/Essential_tremor

My father has ET. I have often watched him use the mouse two-handed. One arm driving tensely (with tremor) and the second hand holding the wrist of the first (with less as not engaged in fine work).

I have early signs. I often wonder if I will eventually be pushed into the grey disability area parent mentioned moreso from UI "progression" than from ET progression

I lived with (not that bad) ET since I've memories more or less, and I'm still under 30. Nonetheless, I encounter daily "difficulties" in doing basic things like typing my code on the door keypad (I miss the correct button and I need to re-enter the code), signing on the POS while the delivery guy keeps it floating mid-air in front of me, etc. Those are obviously nothing compared to real disabilities, but some of them could be easily avoided with a bit of smart design of UI.

Not for CAD/CAM. I’ve tried it, but, for my money and time a mouse is way more effective for managing multiple, detailed selections.

Are you using a 3D mouse?

For you perhaps; I find these very hard to use. Something hand-eye coordination that really does not work for me while a mouse is no issue at all. And I tried because the idea feels nice.