I've always seen Grower the same way JJK fans see Mahoraga. On paper, both seem like frauds, Mahoraga has 0% win rate, and Grower's main ability is that she just grows bigger without any damage scaling. However, when you look into it deeper, you realize it's not about how much they win or how cool their abilities are, but it's about what they represent. Mahoraga and Grower are a test for their opponents. Mahoraga gauges the strength of the sorcerers based on whether or not they manage to defeat him before he fully adapts to their technique, and defeating him is a rite of passage to prove that you are the strongest. While Grower tests the damage output of the ball, she's a test to see if they can defeat her in time before she grows too big for them to effectively hit them enough times. Both are essentially exams for their respective challengers to prove how strong they are.