Nothing in Ethan's graphs says improved "soundstage", "imaging" or "clarity" as described in his advertisement.
That simply is not true. Here's a good example of room treatment improving imaging and sound stage:
See Figure 1 which addresses side-wall absorbers, and the last section about couch and chair reflections. In both cases, "perceived" imaging is greatly improved with the addition of absorption, and the accompanying response graphs show why. Yet again the damage is caused by comb filtering, and yet again absorption is the cure.