It makes perfect sense. I study Chemistry and Neuroscience. These have taught me that absolutely nothing is what it seems. Your brain has evolved to give the most EVOLUTIONARILY FAVORABLE view of the world, shaping it and twisting it to conform. If it would have been beneficial for you to notice every single molecule of air, then you would have receptors that showed you them. Reality can be approached from an infinitude of angles depending on the hardware you are using to look at it with. No two humans see the world alike, let alone two different species. What a coffee pot is to a human is ENTIRELY different than what a coffee pot is to a slug. But at the molecular and subatomic level, whats a coffee pot? Mostly empty space with some interactions of energy taking place. That's all. You SHAPE it into whatever you like.
Neither a wall nor a coffee pot are illusory BECAUSE what you experience under the influence of DMT is illusory. They are illusory all on their own. It makes perfect sense. Real is whatever you choose to believe is real, because nothing exists outside the creator of all: The mind.