Umm, tekmonk:

Andrew Loomis promotes an ARTISTIC (=UNREALISTIC) IDEAL.
He says so himself in his books,

Look up the other Andrew Loomis references: The eye to chin ratio is different between a 6 year old and an 8 year old.
That's because the proportions of a child's face change when it grows.
You have to compare full head sizes.

So your "comparison" is unfortunately skewed.
The six year old boy you posted is 5 3/4 heads tall, btw.
So it matches perfectly with my 6 heads eight years old girl.

(BTW, children DO grow at different rates, and girls are usually shorter than boys)

I'm sorry, but you're the one who obviously doesn't know what he's talking about.