That's not what I get from this at all. To me the infromation is trying to stress that all of the parts make up one whole person. Therefore, when the first alter is created, walls are built up between the experience/job of the alter and the other parts of the original. So altogether, they make up one whole person. The alter isn't created from nothing to add to the person's whole being, it is sectioned off from who the whole being was. So the part that others would call the original, isn't technically the original anymore because part of who they were has been sectioned off to become an alter. Each time another alter is created, it is the same thing: walls being put up to stop conscious awareness of certain things (memories, jobs, emotions, etc.) The idea is to get people to understand that the 'original' as others call it, is not actually the whole person he/she was before the trauma. They are now parts of the whole as well.

As for your goal for therapy, most therapists want to help their patients break down some (or all) of the barriers that are making parts necessary. You want to become a whole person, with all of your parts either integrated, or communicating with each other so that you can access any jobs, experience, emotions or memories needed to function well in life.

Many therapists feel the need to stress that all personalities/alters are part of who you are, no one is a whole person, they each play a part in your system. I think that is where they are coming from, looking at it holistically. One of the roadblocks in therapy that people come up with is that they can't identify some alters as being part of who they are, and they need to overcome this in order to bring them back into a highly functioning person. So this sounds like they are trying to prevent that from being too ingrained in people's minds as they learn about their different parts.

I hope that makes sense.