[Feldkurat_Katz]

Exactly what does the altar server do? From what I can tell, the young boy or girl processes in and out with the priest, holds the book for the priest to read prayers, sometimes holds the waterbowl and towel for the washing of hands

That's because the Novus Ordo mass made altar boys largely redundant. Go to a Tridentine Mass and you'll see how busy altar boys can be.

[Dusty Rose]

I do not think the reference is to servers in the Tridentine Mass, because from what I understand there are no altar girls at the Tridentine Masses. The reference is to girls participating as altar servers in Masses other than the Tridentine, and, from their limited role, I do not see how that should be a threat to anyone's true vocation.