It's generally largely frowned upon nowadays -- largely for social reasons. I recall talking to some folks in Texas about this, and they said, if you could hold kids back for academics, a lot of parents of football playing boys would push to do that. You'd probably see a lot of 18 year old freshman QBs in high school.
I knew a guy who transferred schools halfway through his senior year because it put him far enough back that he could play another year of high school football.
There are some really strange motivations out there.
Yeah. There's a term called kindergarten redshirts, where parents hold their child back to be older for athletic reasons. You end up with these weird kindergartens with some boys just about to turn 7 and all the girls are 5.
