Actually why not ask who promoted Ed Parker to begin with. Parker is self promoted to 10th degree and many of his senior students signed off on his promotion.
In reality there are very few people that are authentic 10th degree levels and even worse most people who go around claiming it are self promoted anyway.
Levels of degrees are all about ego mostly and it is shame that many people forget that a 10th degree is typically reserved for the head of a system that either inherited the system or is semi-retired from teaching and simply oversees the system.
Up until the mid 1960's anyone over the rank of 5th degree was unheard of as that was the highest level recognized in Japan but over the years many people began claiming high ranks and people were duped into believing the higher the rank the more important and skilled the practitioner is. What is any rank above 5th degree anyway? It is an honorary rank denoted to instructors and has little to do with their skill but rather thier ability to teach their art successfully to others. It does not make them tough or great but means they have an indepth understanding of their art that they teach.
Most of the people I know who claim 10th degree paid for their rank through some group such as the World Sokeship Council or other ones that, in reality, have no authorization outside of their own little world. I have met many 8th and 9th degrees that were 10 x more competent than the ones running around claiming 10th. Heck look at ninjutsu...they have all the way up to 15th degree now. When will it end? Rank is nothing but a status level where one stands within their own association anymore...the true meanin has been lost to time.
That is had to say. Years ago not very many people were awarded a 10th Dan. Often those who were didn't get it until after their death. Basically meaning it was on honorary rank. It was a way to honor those that had a great contribution to the martial arts. There have been only a few living 10th Dan.
Today with many people forming their own martial arts more peploe are getting the rank judan.
Different arts have different ways of promotion. Most arts don't get to 10th degree, some do. For some arts, 10th means you have reached full transmission of the art.
Now to the guy who posted above me. You clearly do not understand the Taijutsu (ninjutsu) ranking system. 11th-15th dan in the art is still actually 10th degree, just at a different training priority in training. In order to understand it, forget everything you know about the typical japanese dan grade.
For starters, there is just 3 belt colors. Mukyu (10th kyu) is white, meaning you have no or slight training. 9th-1st kyu is green meaning you are LEARNING the basics. Shodan (1st dan) is where you have grasped the fundamentals of the basics and actually can start moving on with the real training (much like the shodan of any other art). Now here is where it gets tricky. You can start being an assistant instructor at 3rd (sometimes 2nd if sponsored). You are not considered an instructor until Godan (5th degree). You are a master instructor at 10th, but each step after that (11th-15th) correlates to a different level of understanding and teaching. You may find this odd, but the way the belt system is structured actually correspond to the old way that the schools in the system were taught (shoden, chuden, and okuden).
Shoden (not the shodan belt rank but basically means lower levels) comprises the 1-5 dans
Chuden (mid levels) is the 6-10 dans
Okuden (upper levels) is 11-15 dans..
Unlike other martial arts, you aren't considered a shihan until 10th dan, and you can't even begin to hope for Menkyo Kaiden until 15th dan.
So to answer your question, EVERY art is different, and some don;t have 10th degrees. Some have different levels of 10th degree (as I stated above). Only by being promoted by the headmaster or someone higher than you can you ever move up (unless you become the headmaster, in which most either stop claiming a belt level or stop at the highest level they have achieved).
EDIT: forgot two things, 1) a shodan in any art means they have a committment to that art and are good at the fundamentals. 2) somewhere after shodan you quit caring about rank and start caring more about skill.
My martial arts teacher was 5th dan, his teacher who was promoted to 8th dan at the temple in Okinawa after 20 years of study, while in the USMC. Beyond a certain level I think you are also given administrative duties in relation to teaching.