There's nothing worse than not being able to quit something that you strongly dislike doing. There's certainly a chasm between quitting things the second you start to dislike them and forcing yourself to finish everything you complete, no matter how miserable it makes you. Every situation is different, and while it's generally good for parents to train their kids to finish what they started, there must be a limit.
The dad who posted this story is trying to do what's best for his daughter. She's a sophomore in high school, a high-achieving student, and wants to quit doing competitive gymnastics more than anything. She has lost her passion for the sport, is sick of being in the gym 14 hours a week, and her body hurts from the constant training. That last reason alone should be enough for both of her parents to let her quit, but her mom is not budging.
This image is for illustration only, and the subjects are models; the image does not depict the actual subjects of the story.