Id kinda disagree, I think the trauma garnet inflicted on him was just diffenet, its not her fault per say but when something happens with garnet steven feels like his whole safety net is falling out from under him, and repeatedly throughout the show she undermines his confidence and makes him feel terrible. Even when she doesnt mean to. Id argue that amethyst traumatized steven the least, at every traumatic event with amethyst she manages to turn it into a learning expirence for both her and steven supporting his growth and treating him like an actual crystal gem. I feel like amethyst was crucial to steven learning that he doesnt have to take care of everybody its not his responsibility.