You might want to revisit the part of the the story where she knew shite about the world beyond where she lived (due to Rachel), held a body self-image of being ugly and was shocked to be involved in discussions about masturbation, among other things. Yet, she was a young adult at the same time.
Then, there was a series of events where she learned about all of these things, quite gradually, and as her experiences grew so did her appetite for consuming more of them and reaching further than she had previously realized was possible. Eventually, as the strings Rachel used to control her were fully cut and her life was let loose for all sorts of possibilities to grow, all of the limitations on her previously submissive personality were likewise dissolved in symbolic fashion as she told Rachel off in a monumental scene, kicked a long-time bully's ass and decided to formalize a new life with her father in his dual role as her provider and lover.
You know, the entire DMD story up until now.
Sky's the limit on her choices going forward, but she's already showing signs of progressing at her pace - not just that of the MC's helping to lead her quite as much. Their move to a new home was entirely based on her desire and choice, for example.
It doesn't mean she needs to become someone extreme (as you are arguing), but her experiencing things that she (or we) never imagined this previously highly naive, immature and inexperienced character would do should be expected for anyone who was suddenly given freedom to try new things with few limitations and a healthy support system in place.
