I do my CAD and CAM on machines nowhere near my CNC. I like to be able to upload the CAM generated Gcode from where my PC is without needing to go get the SD card and sneakernet it out to the machine.
It’s not that I can’t do it, it’s just something of a bother to go get the SD card, then copy the file, then go back to the machine.
For me, the convenience of being able to upload it via wi-fi was worth the cost of adding a Pi.
Well, now I’m using a Duet board, which has its own wi-fi, so the Pi isn’t connected anymore.
The other thing, of course is that the Pi can have a camera, so you could, in theory, set up a time lapse video of your cut without having to hold a phone steady. I never did manage to get my camera to do that though. OctoPrint is set up for 3D printing, and looks for stuff like layer changes. Not so useful for CNC cutting.
I’m just joking. If you get hooked on electronics and tinkering, the number of pi’s will steadily grow. But you certainly don’t need one to run a v1 machine. It’s just very handy to run things with v1pi, a great quality of life improvement.