Because they themselves are 15 year olds. You rarely actually see people from around 18 up who join regiments that have a <16 leader in charge.
I don't mean to be "that guy," but with all the
stable regiments out there that have been around for years (just using a few), 71st, 63e, my group, KPR, why keep joining, remaking, etc. How is that fun?
To each their own, I suppose.