Thank you for initiating a worthwhile topic! You've put nice energy laying it out. With consideration though, the above is a subjective statement, based on your opinion. This indicates a bias. from which it is easy to build an argument for your personal perspective. Vs direct experience.

You are correct - it's difficult to generalize about the structure of alter systems. I have another view, based on 1) surviving trauma 2) using that as a foundation to build upon the current 'parts' work I do (which is not therapy, it's more like mirroring based on nondual consciousness). If I brought any 'bias' or 'belief' into sessions with clients, that would impact the outcome. Quantum physics. Jung’s emphasis on the most important quality of a depth practitioner is the 'absence of oneself'. In addition, I emphasize to clients, we are changing nothing. Nothing to fix. Nothing is wrong. We are having a reunion with a part/alter. All shadow material is highly sensitive to any 'fix-it' energy.

You might enjoy this dissertation on the philosophy of mind and ontology by Dr. Bernardo Kastrup, which goes in depth on alters & their role in 'reality'. https://www.youtube.com/watch?v=XcMOape0PY8