Most listeners are capable of making good subjective assessments.
Disagree. I did many blind listening tests in the 1990's. Sighted tests are full of bias and that bias colors our senses. It is possible to train oneself to make bias free subjective evaluations of sonic differences but it is an effort and takes some time. Blind tests are required during the process. Most people do not make accurate subjective decisions about audio. They may be useful and they may get the job done for the listener but they aren't accurate at all with comparisons that involve subtle or non existent sonic differences.
Loudspeakers, for instance, have very obvious sonic differences so evaluation results in preference rather than accuracy. Blind testing isn't really necessary for evaluating speakers. We recognize the tone of the voice of people we know because the differences between voices is not subtle. The sound of loudspeakers is also not subtle.
The problems occur when sonic differences are subtle or non existent. People who hear sonic differences between digital cables, for instance, hear what their brains and bias tell them to hear. A blind test can show that there aren't any sonic differences. Eliminate the bias and you get accuracy. That is useful if you don't want to spend hundreds of dollars on an HDMI cable.
How can a power cable affect the sonic performance of an audio system? It can't. This is easily shown with blind testing. Those who spend money on exotic power cables are equipment collectors. That money would have been better spent on speakers and room acoustics.
So subjective evaluations can work in some cases and have no value at all in others. I'm not against being immersed in bias and products of little or no value to sonic accuracy. It is a hobby and there is an entire industry available to feed it. I've been there myself. As I have said elsewhere I am a recovered audiophile so I understand the situation. Blind testing cured me and taught me what matters and what doesn't. It allowed me to quit worrying about sound quality and focus on the content.
If you want great audio have great speakers in a room that is significantly longer than it is wide. That room allows you to put both the speakers and the listener away from walls. Add whatever stuff you need fill the room with sound and enjoy. Use your common sense.