You postings rank is determined by the amount of posts you have made, your user group is determined by the points you have.
I think this is to promote the participation on the site by encouraging the user to create more posts and take part in more quizes and games. Thus creating more points than members actually need to watch their programmes so creating a higher user group status over time. This is all part of the Discuz code that the site is written in.
Hope this helps and what ever user group anyone falls into does not really matter in a case of interesting posts and discussions.
