[kawishiwi]

I think the controller of one of these is both the skier & spotter at the same time. They ski & drive.
The reason for a spotter is to tell the boat capt. what the skier is doing so the capt. can focus on driving. A skier needs the capt & spotter so they can signal to the capt, through the spotter. Clearly in this case the "controller/driver" has a quite intimate and immediate understanding of how the skier is doing. Self spotting? Yes. Self driving? Yes. While skiing? Yes.
Strongest arguments against would be kill switch & concerns that a skier can maintain effective "driving" awareness.