When I started out in this hobby, speaker wire was 18 ga. zipcord...16 ga. if you felt like a splurge. Premium interconnects were Switchcraft. Speaker terminals were screws with knurled nuts, and the Marantz 7, 8, and 9 were still around (but on their way out). The "audiophile" bible was Edgar Vilchur's "Understanding High Fidelity". The most revered recordings by Mercury (Living Presence), RCA (Living Stereo), and boutique labels like Vanguard and The Connoisseur Society were being made...using utterly pedestrian copper wires, vacuum tube recording electronics, and excellent musical judgement. Draw your own conclusions.
On a personal note...
I was in the room when Noel Lee came (personally) to the store I worked in to announce the coming of a new order...in which hanks of zipcord would no longer be given for free with the purchase of a pair of speakers, which was the practice at the time. He spoke with evangelical fervor...and our buyer/owner listened and heard that the Word was Good...for the bottom line. Disciples, copycats, and believers in alternate versions of the Word followed, and the old order was indeed overturned.
The profit motive cannot be ignored in this discussion. I absolutely support the right of every audiophile to buy whatever they deem best for their listening preference. But in the real world environment of audio retail most buyers are not hobbyists, are not skilled in discerning fine differences, and are often over-sold purely for profit.
The OP makes two points I strongly agree with. Musical fidelity is best, perhaps only, discernable based on acoustic instrument reproduction, and cables' contribution to overall system performance is of tertiary importance. First is the room/speaker, second the amplification, then the in-between stuff.