If a child is held back because they are not keeping up with there peers in class, or they seem to struggle with the social aspect I think it is ok for parents to hold kids back. If it is done just to let them develop physically or to wait for a spot on a team to open up it is wrong, as parents we are supposed to prepare them for life after school and for most football will not be there future. I don't understand how holding them back is good for the school like you said unless the only thing that matters is to keep the dynasty alive.