That, and she's come some far emotionally from the first season to the last. I remember when it looked like she was ready to commit suicide in the first season. Like her life had no purpose. I think Season 4, served more as epilogue, and when you look at it that way, it all makes sense. Think back to the ending of season 3, when it ended with Korra just crying. Appearing fragile and broken, and you think about this season, more than anything it was about growth for her. Every season we got a different Korra, and I think that in itself shows the realism of the series. Season one she was assertive and cocky and it ended with her almost killing herself, but having a better appreciation for her spritual connections once she got them back. Season two she was disloyal to a fault, when she left Tenzin to train under Unalaq, ended up losing her connection with Raava too. Season 3 she was almost DESTROYED by Zaheer, and Season 4 she put it all together. She's patient, and compassionate. Yet assertive and vicious when the moment calls for it. She's perfectly balanced now, hence the Book title "Balance". They all took something from her. Amon took her bending and confidence. Unalaq and Vatuu took her connection with her past lives. Zaheer took her physical nature, and state of mind. And by the time she got to Kuvira, she knew how to handle the situation perfectly. As far as growth of a character goes, I haven't seen it handled too much better than it was with Korra. All those losses she took over the course of the series, were indirect wins, and it helped her save the world, and herself.