So I guess DD is a skipping example. She is an age 9, L8 example (or the approximate equivalent). But it may also be a result of our system in the younger years.
In Canada, you can't compete in the provincial system (so like USAG) until you are 9. Anything you do before then is invitational only, and there is NOT a focus on competing at young ages like there appears to be in the US. So the girls at the age of 7 do a meet, maybe a couple the next year, just so they know what competing is like. But they spend their entire time obtaining skills.
When she was 7, she competed in two meets within a month, at old L5. At age 8, three meets within 6 weeks at L7, without a giant. So you can see that for 11 months a year, she was just working new skills. This really allowed a kid like her to excel in the best possible conditions. Her peers (she trained with the provincial girls) would be working routines, as she started twisting on floor, doing saltos on beam, etc. And with few meets, there was little to no stress, and it was all LOVE LOVE LOVE..... achieving new skill after new skill.
This year she turned nine - completely different setup. Nine meets, running from November to May. But she is in a program that allows for the addition of bonus skills to her routines, so whereas she didn't start out with the maximum skills, as she gets them she is able to incorporate them. I see that the speed with which she gains new skills is slightly slowed, as more focus is paid to routines. But she trains more hours, which to some extent makes up for it.
She is definitely not the norm at our gym, and for her age is the only one at this level. But everyone who looks at her sees the same thing - a kid who was likely born to be a gymnast. She looks like Sigourney Weaver from Alien (yes, I'm dating myself) in the form of a 9 year old.
I agree with @
Iwannabemargo if she was a rec gymnast, I likely wouldn't have searched out this forum, so the actual appearance of numbers of kids at this level might seem skewed.