They could use something like an AS5048A for 14-bit (effectively analog to humans) magnetic position sensing instead of a potentiometer or variable inductor.

Considering they already need digital control circuitry to interface to a touch screen it shouldn't be significantly cost-prohibitive to use that to make knobs that are immune to oxidization.

Kinda costly? I wonder if a dead simple 10kΩ B-curve potentiometer would do, though they drift a lot

Just about every analog lighting board I've ever seen has huge dead zones on the end of the linear pots on some channels.

I'm surprised the potentiometers work at all given the abuse they go through. Early desks had no memory, so it was often a huge rush to set the next scene in the fader bank before it was needed.

Yes, I keep a can of contact cleaner around to get rid of the oxidisation.