I would say the position of the government is that there has to be some type of accounting for parity between individuals with different types of disabilities in order to ensure fairness. The 14-hour requirement tries to ensure that therapy has a meaningful impact on the day-to-day activities and living of the individual pursuing the therapy. Where that threshold can be met, there's at least some guarantee that there's parity with those who have to meet all or substantially all tests in terms of the effects of their disability for typical developmental functions like walking.
On May 3rd, 2022. See this statement in context.