Personalities have a function and a purpose, they are integral in our lives, we cannot thrive without each one as a balanced, productive mechanism. Love, compassion, empathy, honor, respect, enthusiasm, joy, happiness, control. What though, if a personality became so mired in the abuse that it could not mature with the rest of us when we aged, grew and learned to relate to others?
I speculate that these parts of our personality are actually self supporting fragments that have been suppressed by us as we attempt to cope with and bury the abuse into our pasts. For example, in order to accept the abuse was happening and yet not be able to escape, we need to suppress our empathy. We certainly do not want to try and "hold the feelings" of the perpetrator as they abused us. The counter to that tact is that we become cold, rigid, isolative, calculating as the fellow feeling we would have for another person is being held down inside us as we are abused, or as we are trying to hide the abuse. We cannot feel or we have limited ability to feel other's pain. This is crippling to us as we seek to learn humanity, as we being abstract thinking in high school, relationships, pets, authority, and our own personal issues. This is just one of the personalities that we lose, and we do not lose exactly the same ones in every abuse case.
Recovery helps to nurture these fragments into maturity, assisting these become to the same level of maturity and depth that the rest of ourselves, mostly cognitive, have matured. If recovery is not realized, survivors can go into a fragmented shock, where the personalities that were not present create a chasm that the over compensated personality could no longer fill. The result? Mental breakdown, depression, somatic response and a score of other "quality of life" degenerates.
This is my opinion only, but it clarifies my search for recovery. What a 'non abused' learns to relate to and internalize during the formative years, I have to recover in my 40's, after a mental breakdown. Unfair? You bet. Impossible? Absolutely not.