Coming from a smaller town background, I find the parents only wanting their kids playing their own grade kind of entertaining. I played basketball in a program that only had two coaches...the "Varsity" coach and the "JV" coach - and most of the conference schools were similar. But JV was what bigger schools called sophomore. The JV squad was all freshman & sophs. Freshman A&B games included all the players on the "JV" squad...the better sophs might only play the first half of the A game, the B game was pretty much all the scrubs play (and I played in B games against guys who got D1 hoops scholarships). We played a handful of freshman-JV game nights where the freshmen only played the frosh game and the junior/varsity scrubs would play with the sophs in the JV game...I was in college before I realized that there were schools that had actual fresh-soph-jv-varsity breakdowns.
Also coming from smaller towns comes unit districts, and summer programs/youth leagues that have multiple ages of kids playing together. Baseball levels were generally two years together - 7&8 grade, 5&6, 3&4, etc...Nobody was scared of playing with kids a year older because they had done it since T-ball and Dynamite football. Some of the better kids might actually moved up and skipped a level, playing with kids 2 years older. I saw plenty of big 6th graders playing on the youth league varsity with 8th graders in football...And some of the smaller rural (and private) schools might have 3rd & 4th graders filling out the 7th grade teams. Rick Schoon, the current long-time St. Anne HS hoops coach, came out of the Wichert elementary (which closed between his 7 & 8 grade years): he played 8th grade level hoops since 4th grade on a team that was like winless (4th grade), winless (5th), 2 wins (6th), went to state in 7th with 4 kids who started 7th & 8th grade since 4th grade. That team learned by getting killed by 7th graders as 4th graders, and by 7th grade they became the bullies.
Manteno's soph team this year took its lumps, largely because 6 soph starters were playing varsity full-time. McNamara I believe only had 17 seniors and 11 juniors, forcing sophs to play on varsity (and that small junior class is why I think Mac is going to not be anywhere near as good next year). Your average 1A school likely only has 40 kids in helmets & pads, so everybody dresses for the Friday night varsity game. Your above average Wilmington freshman is pissed when he doesn't start on the soph team, and the good ones expect to start both ways...Wilmo will toughen up the freshmen linemen by making them run the Oklahoma drill with the older kids the first week of practice - some of the more experienced bigger freshman boys have to learn that they are not going to hurt the high school boys by playing hard (my 20 year old was one, who constantly worried as a 195 lb 8th grader that he would hurt his teammates in practice if he went all out. One round of Oklahoma with the stud 280 lb tackle pancaking him changed his attitude quickly...).