That is an incorrect statement on so many levels.
You don't seem to have learned anything yet here
When you are in the electronic domain - yes everything done here is focused on high fidelity...
But the parts of it that are in the acoustical domain - from Mic and miking methods, through cartridges, to speakers not so much.
To define high fidelity, you have to define how you measure it... no one has defined how to measure (mic) an acoustical instrument in a manner that ensures that it can be reproduced by a set of amps and speakers, and can be psycho-acoustically identical to the original performance of that acoustical instrument. - Achieving this has a heap to do with miking and mastering techniques.... and just as much to do with room acoustics, speaker design and signal processing at the room and speaker level.
One of the key things here is that the high fidelity measuring stick is just as much driven by PSYCHO acoustics - ie: perception / subjectivism
If you want to approach it in a purist objective manner - High Fidelity could potentially be defined by placing a mono mic at a predetermined distance from a set of speakers, where it is intended to reproduce the acoustical signature recorded originally by a mono mic at the acoustical event.
The resulting secondary recording would be compared to the primary recording, and could then be graded in various ways.
Ideally the recording in both instances should be done Binaurally (ie: dummy head, with mic in the ear)
This way you would potentially have a measure of "High Fidelity" - how useful this would be in analytic terms, as a tool to target improvements in that chain, would be quite a different and open question!
One of the advantages of such an approach, would be that it does not require anything fancy.... it could be the tester standing and reading out a sentence. More complex and less frequency limited sources, would be more challenging... but getting the human voice 100% right is already a feat beyond many purportedly high fidelity systems!
One of they key points, is that it is a differential measure - ie: you have included everything, and not merely measured using any specific artificial signal - it is a recording of an acoustic space and event at a point in time - compared to an attempt to reproduce the same acoustic experience at a later time.
If the original recording is NOT of an acoustic space - eg: it is a purely or partly synthesised soundtrack - whether by use of electronica, or due to the method of miking and mastering - then you have nothing to compare it to. - There is no yardstick.... - You can maintain the waveform/soundtrack produced by the mastering - you can measure it and endeavour to reproduce it correctly all the way to the amplifiers.
But once you hit the acoustic domain - the speakers - there is no way of determining whether or not it is high fidelity - it never previously existed in a purely acoustic space.... (other than possibly at the mastering studio or the mastering engineers headphones!) - there is no possible way to define whether or not it is indeed high fidelity (question being of course, fidelity to what?)