Very few people have seen 360° potentiometers, I worked manufacturing them from 1977 to 1980. The only place ordinary people would have encountered them was if they got a PerkinElmer CT scan in the 70s/80s. The machine motion was monitored by 3" diameter sine/cosine pots that cost over $300.00 each in thousands.
Also lots of military gear and high end science gear had outrageously expensive 360° rotation potentiometers with all kinds of output functions. I suspect that Honeywell, who bought up nearly all the 1970s precision potentiometer companies, still sells 360° potentiometers on a custom build basis.