Alun,
Why don't manufacturers provide the best power cord for their electronics? Perhaps it would add to the cost of their final products or perhaps the best cable does not exist and is therefore subjective. In either case it is prudent that manufacturers only provide utility cables and allow the end user to pick and choose the cable that delivers the sound they are looking for.
Why don't speaker manufacturers provide the best speaker cables with their speakers? Alternatively, why don't electronics manufacturers provide the best interconnects with their electronics? Some manufacturers do provide cables but these are Mid-Fi components that hardly represent High End performance. Is it that far off before this debate turns to all Amplifiers, CD Players, Pre-Amps, etc. sound the same? If so then reports of Stereo Reviews demise were premature.
Perhaps the abundance of electronics, speaker, and cable manufacturers exist because electronics, speakers, and cables do all sound different and perhaps it is these differences that people are attracted to.
LM