Most people don't get it. Expected.
Proffessional stage, set designers know very well how lighting and dark color can unleash the imagination. Las Vegas, Broadway, Disney set designers, all know these methods. Yes, it's a real thing.
It has NOTHING to do with the color of the speakers. It's about creating an illusion of a black abyss that makes the back wall MUCH deeper. This allows the listener to 'see' much deeper into the sound stage.
If you have a dedicated listening room but you can't change the color of the back wall? Spend thousands of dollars on equiptment and then have a room of visual distraction makes NO sense.
Done properly it's looks very clean and dramatic and blends perfectly into the rest of the room.
A huge mistake I see frequently is a fireplace down low, with a big screen TV up above. Speakers left and right. NOTHING could be more distracting to the music experience.
You tell me...what is the main focal point in this room? The fireplace? The TV above? The vibrant wall color? It's surely NOT the stereo image. There is NO place for the music performers image to appear! Is the singer standing in the fire???
Nothing could be more distracting and detrimental to the image than all this clutter.