You can only play 10 players at a time. So while hopefully your best players are upperclassmen the rest sit on the sidelines. How is that good for development. Game experience rather than bench experience is a bit more important. Coaches bring up underclassmen to Varsity because mommy and daddy complain and are flabbergasted at the fact that their son is on JV. These parents say things like" he plays for this travel team and I pay this much for training. He should be on Varsity " So coaches bring them up and they ride the pine. That's really a good way to develop talent.
Stupid is as stupid posts and this was a typical stupid post - lets start with PW where they bought up an 8th grade goalie who started for 5 years and was a big part of them being competitive. Most of the better programs will have 9th and 10th graders contributing to the varsity teams and those are the kids who become the stars and leaders in 11th and 12th grade - the ignorance is the thought process that if you are not brought up by 10th grade you wouldn't be a starter or contributor as an 11th or 12th grader and that is just not the case - every school has 12th grade first year starters. At the end of the day the best players play regardless of grade.