I’m a trauma-informed therapist and a moderator here and generally agree with your position. In fact the more I’ve studied how to help people who are traumatized the more I have recognized that plurality or fragmentation of the self is present in most people and gets more intense/exaggerated when someone has experienced trauma. DID (dissociative identity disorder) is at a far end of the dimension of structural dissociation but most of the folks that I work with experience some degree of it, often taking the form of unresolved ambivalence, mood swings, numbness or a constricted relationship with one’s emotions, etc. Where I do disagree a bit perhaps is that it is most often the case that there is a relationship between the exaggerated presence of “extra people” or “parts of self” in a person’s system and the incidence of those troubling symptoms eg., amnesic barriers, troubling internal communication, involuntary switches. It’s theoretically possible to separate these things but in practice they tend to co-occur. I do agree that the symptoms are the problem and not the plurality though.

Edit: I think implicit in what you’re describing is that people who recognize their plurality are not necessarily psychotic (as in having symptoms consistent with schizophrenia eg., hallucinations and delusions), which I very much agree with. I have met DID folk who had psychotic parts (delusions of grandeur and god-like powers) but that was just a part of them; not who they were as a system.