If any minor uses his adult friend/cousin/relative to pass the KYC, this is morally not correct. Although the gambling site may not be able to trace it but it is not good for the minors to play gambling. They are not mature and can misuse the funds of their family.
I concluded that the KYC procedure is necessary, although I personally do not like it.
KYC, this is an unpleasant procedure for anyone, because most people want to remain anonymous, but it is necessary, first of all, for your own safety.