While I don't think it was stated very clearly, the impression I got from the grandparent poster was that in many cases metrics actually distract from the thing

While I don't think it was stated very clearly, the impression I got from the grandparent poster was that in many cases metrics actually distract from the thing we actually care about, in this case "how does it sound?" You can't really represent that as a number, because in one case "rich resonant lows and a warm sound" might be what you're after, while in another "crisp, distinct highs, and extremely high fidelity" could be preferable, and it is the gestalt that produces the aesthetic quality.