"The reminder to professionals about alters not being individuals is to make sure they understand they need to push home to their patient that they share a singular body and in turn a singular life."
This is literally exactly what I'm saying.
And I'm aware professionals are encouraged to use the languages their clients use, I'm not saying you literally have to call them "parts" if you don't want to. What I'm saying is that the core of the disorder is dissociating away from parts yourself and disavowing them as different people or entities, and you are never going to heal from a disorder if you are just constantly reinforcing the core of what makes you sick.
You have to strike a balance with DID treatment. Alters need to be acknowledged and engaged with as they are, you should not be ignoring them or trying to "get rid" of them. But as I've said, doing the complete opposite of that is harmful as well.
Integration refers to processing your memories, personality and identity as all being part of one cohesive whole. Dissociation refers to the separation of these parts and the disavowal of them as being part of the same whole. There is no way to achieve integration while still dissociating at the same time, they are opposite processes.
I'm not saying there is only one way to recover from DID, because as you said how integration presents exactly can vary from person to person. But all integration involves processing dissociative parts as being parts of a whole. That is quite literally the definition.
Claiming that pointing that out is to say there's only one way to heal from DID, is like claiming that "you need to eat to recover from a restrictive ED" is also saying there's one way to heal. There is variation in recovery, but you always need to address what's at the core of the disorder.
A few excerpts from the Haunted Self that I was referring to here:
"Even though dissociative parts have a sense of self, no matter
how rudimentary, they are not separate entities, but rather are
different, more or less divided psychobiological systems that are not sufficiently cohesive or coordinated within an individualโs
personality...These systems are part of a single human being, so we have chosen to refer to the entire individual when he or she is directed by one of those unintegrated systems."
The degree of emancipation of parts varies. Some have a
depersonalized awareness that they are part of a larger personality: โI know Iโm part of him, but it doesnโt feel like it.โ Others realize this
only vaguely, and a few regard themselves as an entirely separate
person, even when confronted with obvious evidence to the contrary. This can lead to serious problems for survivors.
Various ANPs and EPs may have a strong investment in the
belief that they are separate persons. This substitute belief must be
met with gentle but consistent challenges by the therapist. If parts
insist on being called by another name, the therapist may do so, but
also should regularly refer to such parts as aspects of a whole person.
I hope this better illustrates what I'm talking about, because I really don't think we disagree.