I can't see the relation of it from why advertisers pays higher stake for higher ranks. And my explanation is likely to be the reason why they pay for good for higher ranks, due to the signature space and color, characters that it can provide.
I think that he just believed they are more experienced and already know how to go about creating awareness for their projects more than the junior members since they have been actively participating in the forum with quality contents which they also believe they will get that quality contents from them.
So, instead of us doing comparison, the rank is left opened for anyone who wishes to take up the title in order to get qualified for such treatments high ranked person gets by walking his way through it through the necessary efforts required. I believe that one day; every junior member too will attain that rank provided they constructively participate in the forum.