The issue I've heard with E64 is that different clubs are handling it differently. For some it's been used as an exclusive level for a team, but the complaints there are that there haven't been enough games for the team. For others, it's a way to mix and match (since card registration is flexible) players from various teams but they have other responsibilities (and more games) with their NPL teams etc. Does that match your experience, or do you have a different take?
I also think even in the girls side (which the complaints are always raised here that it is diluted) that ECNL is a very different creature from ECRL.
Not all positions are equivalent in producing an excellent team. For example, you need a competent goalkeeper that is not going to let in expected goals but at U14, even on the boys side, 90% of the keepers even at the highest levels are going to let in that shot that's banged in over their heads between themselves and the cross bar. A kid on the lower end of the league chart may have a worse save record due to the amount and types of shots the kid is facing even though objectively as a shot stopper he is better than the goalkeeper on the first team on the chart. The goalkeeper can't win games for you....he can only lose them for you....as my son's middle school rapidly discovered despite 3/6 clean sheets and multiple multiple shots on target....if the strikers don't score the best you get is a 0-0 game assuming not own goal mistakes from anyone or shots outside the expected bubble (such as penalties, 1v1s in the 6, high corners or cutbacks). So from a shot stopping statistic, it's only valuable if you know the expected goals the keeper would let in for that age and for that level.
And that's before you get to the point that the goalkeepers (100% on the boys side because of the American/MLS possession style of play MLS Next implemented) at the higher & older levels have to have good feet AND are also responsible for backline tactics. The strikers are an easier statistic...goals scored, but that also has to be weighted against expected opportunities (if the striker doesn't get the ball, the striker can't score). It's the Ted Lasso "get it to Zava" problem. The striker position also has to be weighted much heavier as whether the teams wins or loses turns disproportionately on the skill of the striker, which explains the high salaries for the position as outlined in Soccernomics. A center back is another one of the key positions that needs to be weighted and which economically as a result comes with a salary boast, but there scoring statistics would be of little use and a more reliable indicator would actually be height and backtrack running speed. The value of the RB/LB in part depends on the method of attack being used by the team....are they being used high to attack (in which case scoring might be part of the moneyball indicator) or are they being used in a more traditional line defensive mode.
Basketball used to do this and assign a number to players, at least when I was growing up. The positions are less specialized since all the players are expected to take a defensive v offensive roll. But even then it was never very useful. They used to try to balance the teams with those numbers but found that it didn't also work. AYSO does the same and has the same issue, but less so since they are primarily focused on the little ones right now and the statistics are more meaningful when soccer is about running and shooting than positions and tactical play.