Real-world devices simply aren't that accurate.
Agreed. However at around 1% distortion we start to have trouble to hear or identify distortion. At best speakers may have 0.3% distortion over their entire frequency operating range at full power (if they are exceptional quality).
Perhaps the point Peter is making is that extra ultra precision in modern line level analog equipment can quickly approach "diminishing returns" given the acuity of our hearing and the relatively crap performance of speakers and room acoustics in general...
Agreed, "perfect" is completely the WRONG word... as Kijanki points out NOTHING IS PERFECT... (except my wife and kids)
"Good Enough given the sad inadequacies of other audio system equipment" is more like it but "Perfect" ....certainly and absolutely NOT.