Let's put this in a way everyone here can hopefully suddenly come to a logical sense instead of linking stupid YouTube videos as evidence that this is what you should do.... Yes, because personal individual YouTube videos is way more suffice than medical and scientific evidences over the course of multiple participants
Do you support having people marry 8-year olds like they do in Islamic countries? No? Then why would you support someone potentially fucking up the rest of their life with something they could potentially utterly regret in 10 years?
Same goes for marrying an 8-year old, they might be happy and think it's fun at the time, perhaps not so much in 10 years. The purpose of not allowing this is for the protection of the child for a decision that should never be able to be made at an immature age with a developing brain and developing hormones