Your personal experiences sound very interesting and I don't mean to detract at all from the effect they've had on you and many other people. However, I was a neuro Phd student and did many 'default mode network' studies using fMRI and it is -very- early to be making claims about the nature and/or purpose of this network, or how it's perturbed by any experience: psychedelic or not. The level of temporal and spatial resolution of data gathering of this and other brain networks is entirely too coarse to make legitimate inferences. At this point in the literature it is a very good story with a few compelling examples but not nearly complete enough to make real claims.