exposure - Why can't ISO, shutter and aperture speeds be controlled more precisely rather than sticking to a fixed scale?

Each camera supports a standardized scale of ISOs, shutter and aperture speeds, adding or removing one stop of light at each value. Some cameras also support 1/3rd stop increments which adds a bit more of a scale.

But why can't the speeds be controlled more precisely, down to (say) a single ISO percentage (101 ISO) or a single aperture point (f/7)? It would obviously be too tedious in manual mode, but wouldn't the automatic exposure modes benefit from having more graduated controls?