I remember the first time altar-girls were allowed in my local parish church, when most Catholics were conned into the NO Mass. I confronted our parish priest and told him it should not be allowed. I said the first road to priesthood was by way of altar-boys. If you let girls serve Mass the boys will opt out and vocations would be lowered, I said to him.
This is deeper than most people realize.
Psychologically, men and boys DO opt out when girls invade a sphere, especially when they excel there. For example, education. You can EITHER tailor to the boys or the girls. Impossible to tailor to both, since boy and girl brains are wired completely differently. As the saying goes,
if it weren't for the fact that men and women can reproduce and produce offspring together, a solid argument could be made that men & women constitute different SPECIES. That is how different men & women are. And the differences show up right away too, within the first couple years of life!
So when the boys see the girls getting the best grades (naturally, since Education AT ALL LEVELS happens to be tailored to the female mind), boys "check out" and decide to place their eggs in other baskets -- like sports, where girls physically can't keep up with them.
Boys are naturally competitive. If they see themselves losing, they naturally cut their losses and begin investing themselves elsewhere. Boys/men have a natural ego. It's basic human psychology. The same way women need to be loved, and require consensus to be happy.
A J*w -- or anyone who understands human nature -- could have seen this coming a mile away. They probably did. They came up with Altar Girls very much on purpose. They knew what they were doing.