Plenty of other sports leagues go by grade. They work well.We get it, You want to stratify by grade and make it all "School ball".
Oh wait, except for those parents that "red shirt" their kids.
There's no standardization with that either. In our area, the cut-off to begin kindergarten is different between school districts. In NYC you start school if you were born on or before 12/31, so birth year works great for them.
I don't understand what the advantage is. My September birthday daughter will basically be sitting out the spring travel season in 8th grade while waiting for her travel age peers to finish their school season.Girls with September, October, November and December birthdays have the advantage once school ball starts.
Girls with September, October, November and December birthdays have the advantage once school ball starts.