Yes, that's my understanding too. All our parts are there for a reason. They can change, but not be gotten rid of. I was really taken aback to find I have a part, or several actually, that think they are one of my abusers. But then when I started looking for information I found this is not unusual. It makes sense: child is abused. Child creates a part modeled on the abuser. That part serves as an internal censor, as if the abuser lived in his/her head (uggh) giving advice on how to behave to make further abuse less likely. In a convoluted way these parts are protectors. On the down side, the internal model of the abuser continues this task long after it has stopped being necessary.
When I first became aware of this, I also saw exactly how this part of me came to be. The split happened at the height of one of my childhood traumas. I have the feeling I need to do lots of work processing that moment. Then, yes, hopefully I/we can find those parts something more up-to-date to do.