The sport hasn't grown because of prefirst or holdbacks. Its grown because football and baseball numbers are down and soccer lets just say sucks. And its a fun game that kids like to play. The u15 u 13 model etc isn't needed because numbers are up. The cleanest way to play is BIRTHDAYS...simple.
Thank you logical person.
OP - "I like holdbacks, sport is growing, ergo holdbacks are driving the growth of the sport." Talk about a strange narrative...