Is it this report you're talking about?
https://www.mja.com.au/journal/2017...first-national-audit-children-and-adolescents
It's a bit of a leap to say that because 33% of T1 Oz youth are overweight and only 27% meet targets that DAFNE/ liberal attitudes is to blame. By the way, the 33% compares to 27% in the general population and I'm not aware of any non-Ts doing DAFNE, so it's much more likely to be external factors.
Quite apart from the fact that not all T1s have done DAFNE, teenagers are teenagers: you could send a lot of them on any course you like, DAFNE, keto, paleo, lchf, the chances of them all sticking to it are minimal - teens do what they want. How many teens do you know who say, nah, I can't do that because my nurse told me not to?
Let's be blunt about this: some people are overweight because they eat too much. It's nothing to do with evil carbs. It's not what you eat, it's how much, and knowing when to stop. If I put my mind to it, I could end up overweight on a nil carb diet if I ate too much bacon.
I regularly eat carbs and have done so since dx almost thirty years ago. Give or take a few kilos, I've been the same weight all that time, BMI is 25, a1c is 36, AGP graph from libre is reassuringly tight, yet paleo/keto/lchf people will still say, ooh, pasta, you're taking risks there, mate! No I'm not, because I know to stop eating when I'm full.
I found the DAFNE course very useful. At no stage was there any sense that I was being told I had to eat carbs. It merely provided methods for calculating bolus for those who choose to do so. If people then head out the door to the nearest McDonalds for lunch, then hit the pub, then a pizza on the way home, that can't be laid at the door of DAFNE.