This seems a lot like the internal family systems model of therapy. My T uses an adapted version of it with me and my alters, and it works really well for us,. But then I am an avoidant client so am very happy to find ways to take care of my selves by my self, without much need for the T except as a guide. I don't really want much from the T in the way of comfort support or connection.
In therapy we use this kind of way of viewing the parts (in my case fully formed alters) to solve problems within the system and it works really well. We are able to quickly accept different alters and respond to their true needs and intents quickly and compassionately. The skills we take with us out of the therapy room and can use them between sessions to manage internal conflicts and regulate emotions too.