Sure, sometimes it is discussed whether or not children can transition medically (p.s: it’s why they have to go through an army of doctors and psychologists), but to deny that the debate doesn’t revolve around if someone is happy or religion is ignorant.
Countless times I have seen people make the argument that transitioning has a high regret rate, countless of times I’ve seen people invoke religion and try to say being trans is a sin (what with the whole bible quote about men not wearing women clothing).
So when people debate about trans people, 90% of the time it is about someone’s happiness and getting in the way of it.