Right now in international politics, USA, China, and Russia are the top tier. Next tier is UK, French, Japan, and Germany. 3rd level is India, Brazil, Indonesia. 4th is Austrailia, Italy, Canada, Mexico, South Africa, South Korea. 5th is like Vietnam level.
As we can see, in this G7, there are 2 top tier, 3 third tier, and 2 fourth tier. In comparison, in the current G7, they have 1 top tier, 2 fourth tier, and the rest 4 dominated by 2nd tier. G7 is influential due to this large bloc of 2nd tier.