no not always. Here all extracurriculars (even outside of school) are done by grade level currently in NOT by age. So my currently 7.5yo 1st grader who is as big as his 10yo brother is playing baseball with kids in kindy and 1st grade. So the age range on his team is 5.5 to 7.5 yo... not only does he tower above the rest of the team, but jut his physical skills are way above those that are not yet 5 and just turned 6. We are always trying to move him up a level.
We had no choice as the state the year we could have started him in private kindy closed the loophole. Before, you could start a child who turned 5 during the school year in private kindy and then move them to public 1st grade the next year. The state got upset about parents doing this so closed the loop hole and would not accept a child into 1st grade unless they were 6 by the cut off date.
One more thing about holding kids back a year. It can give kids a competitive advantage later on in sports, academics etc because they are competing with kids over a year younger then them in the same class. We already see this issue with my late october b-day boy, can you imagine if he was a January or March baby instead and was already 8 and in 1st grade!
Finally, my 7 yo boy has less in common with the other 1st grade boys in his class. He has more in common with the 2nd and 3rd grade boys. He's more social then his classmates, more mature, and being older he gets exposed to much different things then his grade level classmates.
Yes there always has to be a cutoff point, I just wish there were ways to bend those for some kids, so one like mine, can be more with peers he has more in common with.
Mind you were were urged by my oldest son's first school to hold him back a year, but we just couldn't see him being anywhere from 4 months older (right after cutoff) then other children in his class to being 1.5 years older (right before cutoff) versus being in the middle of the class age wise. I mean he would be taking drivers ed at the end of 8th grade!