The way Dr. West explained it is that most of us can fairly easily focus on a conversation in the midst of a busy room where lots of folks are talking. For him, the other conversations in the background pose a challenge for being able to clearly hear just one.
Similarly, many speakers deliver a diffuse image that varies by frequency so that the result loses that sense of realism. Sound Lab speakers sound realistic to these ears even when you hear them from a different room! As a previous Acoustat 2+2 user with a nearly “head-in-a-vise” sweet spot, I find that the image varies little regardless of my position in the room. Up close. Far away. Sitting down. Standing up. In front. Behind them. I am lucky that I have a dedicated 25’x16′ room where I am able to position them best. Which for my room means they are about 8′ from front wall which is close to the “Rule of Thirds” concept I learned from mentor Harry Pearson.