It all comes down to who is in charge and how the JFL is being ran. The main question: Is it about development or winning/stats? I see the biggest issues with how teams run their offense. Too many times you see teams just give the ball to the fast kid and hope everyone else can get in someones way not actually blocking. Sometimes it's certain kids play every down of a game while others get 5-10 plays only. These kids show up, work, and aren't rewarded with playing time because getting a win is more important than their development. Striper rules are some of the worst things to happen to bigger kids and have probably driven more quality lineman away. Add to this some dads treat football like the 1980's and do way too much conditioning and full live tackling drills. It is a recipe to drive kids away.
Then you see teams where playing time and experience is important. They also get coached up. They run the HS system or have enough knowledgable coaches to teach proper, age appropriate techniques. The HS that get these kids are at such an advantage over their peers.