Earlier quoted context omitted.
Digital effects pedals have trouble emulating the nonlinear behavior of vacuum tubes, so I imagined the same issue would come up with mechanical implementations. I've never heard a digital trumpet that sounded much like a real trumpet. Digital implementations also often suffer from being too perfect.
You won't hear a trumpet suitably emulated by motors either. But that wasn't the question. Any motor-based oscillator can be accurately emulated by a digital oscillator, so the answer to the original question is "nothing." But yeah, neither is good enough to emulate a trumpet played by a human.
For synthetic sounds however, at this point I think it's mostly a question of workflow. Like yes you can take time to program all those imperfections into a digital sound. Or you can take time to make an analog device which has them inherently.