You hit the nail on the head!
Stock control arms are designed that the pin in the bushing is fixed and does not move with suspension defection, only the rubber twists. The pin is not just a round pin in the rubber, it has protrusions that meld right into the rubber bushing.
Aftermarket bushings like poly want to rotate on the pin or have no ability to deflect for suspension movement. Rustys sells heavy duty arms, but the bushing they put in there is not molded to the pin, so after a few good bumps, the rubber delegates from the pin and the bushing wears out fast.
Hind joints are a totally different animal, but again, the pin does not move.
Lots of people think the suspension moves on the bolts holding the arms in place, the don't and shouldn't.