So I don't think anyone should be able to promote themselves or claim they founded something without either proving themselves first or putting their theories to the test or at least putting them out there to be tested.
This should be the way possibly but who is to say what level of proving themselves is enough? And what is the proper way of proving their theories or testing their new way? Now these are rhetorical questions as no one decides who has the right to form ones own system of defense. And if someone wishes to follow that way is up to them. The tail tale sign is the longevity of the new system.
As to your question of why rank. We all know it was started by Kano to chart progress, but I think it went beyond that as the world changed (ie we went to war) I think this influenced the concept of rank since moo means (loosely) military, the old instructors wanted to feel more inline with what was happening at the time. Of course, there is no hard evidence of this, but the martial arts grew up almost hand in hand with the military in the beginning to middle of the 20th century.
True martial arts grew up with the military and actually was the military in some places. In Korea the military soldier all hold Dan ranks as part of their training. But the martial arts have always had martial levels if you will that was done of a family type status in China, like grandfather, father, elder brother and student (son/child). In Japan the same type of thing was done but they also used menkyo certification as well as titles.
Another way to illustrate Kano’s tie to sports is the belts being a direct link to the bands swimmers used to denote levels of proficiency. And taking the Dan/kyu structure from the game GO.
The rank structure is skewed or distorted from what it once was. Testable levels above 3rd or 4th Dan was not the plan, and that in it’s self can show how far it has gotten off tract.
As a founder, then yes you are now “above” rank if you will, because you normally don’t hold rank in your own art. Why? Who above you can promote you? Now some will hold/claim their old rank. Or go outside their own school for moving up the rank latter. The reason promotion board from ones own group is used or an outside ranking boards is used is because it is distasteful for many founders to claim “I am a founder so I hold a 10th Dan”.
The topic is a sticky topic as Dan said earlier, but even more so because people see rank as different thinks from school to school and art to art. This is why there is no rank value out side your own school or association.
Brad