They do. All you have to do is listen. The difference between you and me on this point (aside from your belief in numbers over the live experience) is that I listen and enjoy, and you merely listen and read.
Transports, cables, and how they both combine with different DAC's do make differences. Of course, if you are, er, "sonically" challenged, you may not hear these differences. Or, you may be merely prejudiced in your reporting of the argument.
But anyone who loves music can hear these differences. Subtle or obvious though they may be, music lovers hear them. And they matter.
If you don't hear them, perhaps a trip to your ear doctor could clear up the problem. Of course, if you have cognative problems in processing the signals, then perhaps a good Neurologist (or shrink) could solve the problem.
Those of us who can hear, listen and make the adjustments. Those or you who cannot hear, simply rail against those of us who can.
Hey. Thank your lucky stars. You get to live on the cheap, without ever knowing what you are missing.
You give "deaf and dumb" a new, transcendent meaning. Just turn 'er up and enjoy.