It's not impossible, but it is very difficult. In a country like the USA and the UK this system makes no sense but we have different needs in Australia.
The IDP program is a separate levels system for kids working towards elite and their levels go IDP 1,2,3,5,6,8,10 and then junior and senior international. The kids train and compete in a whole different stream. Kids usually enter at IDP 1,2 or 3 which are aimed at 6-8 year olds. But can enter as late as IDP 5, which is usually 8-9 years old. In order to reach the higher IDP levels they must test through the lower levels. So if a child is not identified by IDP 5 then they are not eligible.
Then we have a whole separate levels system for the majority of gymnast which is level 1-10 and the stream that most gymnasts and clubs compete in. It could happen that an outstandingly talented gymnast goes through the regular levels system and is granted permission to transfer to IDP at a higher level but this just generally doesn't happen.
Australia has only a population of 23 million people, countries like the USA have 46 million children alone. We don't have the gyms and the expertise all over the place for a regular gymnastics club to take a kid to the top. We run specialist High performance center's where the top coaches in the country teach the top kids. Most gym clubs don't even produce level 10's let alone elite's. We need to have a central program to pull the small number of kids together who have this talent.