I think you’re right. With the old Mass there’s a certain discipline that goes along with serving as an altar boy. I’m always amazed at seeing the young boys - and I mean 7 or 8 years old - kneeling with ramrod straight backs while holding their hands perfectly together in prayer. You simply can’t find that sort of patience and discipline in kids today.
At my mother’s funeral Mass, yet again I witnessed sloppy girls (dressed as monks!) running around the altar seemingly without knowing what they were doing. In my youth and at the Tridentine Masses I’ve attended in NYC, the altar boys are so well-trained they are practically invisible. They were not and are not a part of some “show”.