Throttle cables on 50 year old vehicles work just fine.
No, they don't. They require regular maintenance, like very other mechanical part on your car. My 1980 Mercedes and equally old Honda motorcycle are both cable-controlled. The linkage in the Mercedes is all sorts of worn out, to the point I can't accelerate at full throttle anymore. And guess what? Mercedes doesn't make those parts anymore.
Several have had tps issues.
A Throttle Position Sensor, as you understand it, is not used on electronic throttle bodies. At all. Inside the throttle body, the stepper motor itself (which is not a potentiometer) feeds the position back to the ECU.
And good luck buying one when they stop making the exact model for your specific vehicle when the factory in China quits making them.
TPS sensors were often shared among several models in a lineup, sometimes carried to newer models, and even over different manufacturers at times. They're stupid simple to make and fix.