In essence, conversion therapy, reparative therapy, ex-gay therapy, et cetera, are all attempts at brainwashing. They vary only in their degree of cruelty. They make no more sense than would an attempt to make blue eyed people conform to the majority and become brown eyed.
I know someone who went through this "therapy." He was not made heterosexual, but he was made miserable. It took years for him to get back to a state of mental health.
Most parents want the best for their child but they can be misinformed about what that is. That makes it necessary for the government to have public health regulations such as this.