I don't think that what you are comparing is the same thing people are talking/complaining about. We are not talking accuracy of the reps, we are talking production faults. That is very different.
It is indeed very interesting to compare a rep vs gen and see where de diferences are... Can be handstack, shape of hands, font, colour, case shape etc.... That is what we do on this forum and discuss, this is why there are frankens, to make the design flaws disappear, but that is not what QC is for...
But you don't want a hair in your dial, misallignments that are obvious, smudges here and there, that is why qc is important... That's production flaws, not design flaws.
you are truely right about the quality of what these rep makers can achieve, therefor it is a pitty that they can be so sloppy sometimes, because we know they are capable of great things!