Yes, there are restrictions on the minimum age for IDP but not for NDP (except the one rule that you need to be 5 by jan 1st to compete).
The reason for the age restrictions is because IDP is a very specific developmental program designed to prepare athletes to be of the appropriate standard to represent Australia in International competitions. Ideal preparation for an athlete is not just to introduce everything as early as you can, some things should not be introduced to early before the body has gone through specific developmental stages. The program is mapped out in order to have our kids peak at the age where they can be internationally competitive, a big issue for gymnasts is peaking too early. They can be super talented at 12 and not useful competitively by 15 because their bodies have done too many of the wrong types of exercises too early on.
NDP does not have a minimum age on levels because traditionally if a child was good enough to be of that level by by an age that would be considered too young, they would be pushed towards IDP anyway. Also its really not an issue, we have not really had a problem with NDP kids being too young. What is the youngest level 5 you have ever seen? What is the youngest age you have seen at level 7? Australian NDP athletes are very rarely excessively young for their level, so regulations have not been needed to stop coaches from pushing kids up too early.
