why do people feel the need to buy expensive cable

Mamboni probably has more experience in all aspects of music including listening than most anyone in these parts.

There are many ways to tweak effectively but I'd think twice before discounting what he said.  It makes perfect sense.

Mapman, With all due respect, I don’t believe I misunderstood, I simply haven’t had the same experience at all in more than 40 years at this. And I too have a very solid reference in live acoustic performance. Perhaps this is a preference???

For the same reason people are cheapskates.
There are different levels of expensive and cheap and I never shoot for the bottom be it audio, bicycles or guitars. Ever.

Two different ways to tweak in my opinion. Very much a matter of preference and goals. However with good quality modern digital processing technology its very quantified, measured and reliable to an extent not possible otherwise. Like most things in audio many ways to slay the beast effectively for someone who knows what they are doing.

"Using exotic cables to achieve a desired sound is not cost effective."

That statement is actually an excellent example of what is known as a Strawman argument. Misstating the opposing side’s position. It’s a common ploy of those who object, perhaps strongly, to expensive high end cables to portray cables as some sort of tone control device, as if the high end cable manufacturers are engaged in some sort of global conspiracy to manipulate the naive and gullible audiophile. And that audiophiles purchase high end cable to control some audio characteristic or another, you know, tame the highs, get more bass frequencies, etc. Furthermore the determination of the cost effectiveness of a given cable or a given anything actually would require a formal system engineering study, not an off-the-top-of-the-head opinion.