Dont believe me? Do some research, look at the history of the art! Look at the beginning when Grandmaster Carlos Sr. was trained by the Japanese. Look at what Grandmaster Carlos taught and shared with his brother Grandmaster Helio. To quote Grandmaster Reylson Gracie, son of Carlos Sr., "Although it is true that ninety percent of fights will eventually end up on the ground, ground techniques are just a portion of Gracie Jiu Jitsu. What makes Gracie Jiu Jitsu such a wonderful art is that it contains the strikes and kicks of Karate, the ground fighting techniques of Judo, and the joint locks and throws of Aikido."
There was no such thing as Berimbolos or Imanari rolls. If it didn't work in a real fight with someone also trying to punch or kick you, it wasn't Gracie Jiu Jitsu.
If you come from traditional GJJ there was only 3 belts: White, Light Blue, and Navy Blue. You could train for 30 yrs plus and never earn another belt, and stay a white belt unless you were accepted into the instructors program, at which point if you completed it you would earn a light blue belt. You would stay there until you wanted to become a fulltime instructor, and then you would go through the professors program and earn your Navy blue belt. This process could last anywhere from 2-4 years on average. If you had prior training and experience that was taken into account, and GM Carlos Sr. and GM Helio would or could shorten your time to obtain these belts/positions.
Listen to GM Helio talking to the Valente brothers about rank:
The idea of the modern BJJ rank system came later, and as the sport grew, the time in grade grew. Instructors began holding students back from promotions so they could do better in competitions against someone of the same belt color. There were many other reasons too, I am sure, but the point is that in sport BJJ it may be important to wait 12-15 years to earn a black belt. After all, everything above Blue Belt in sport BJJ is just learning how to fight other BJJ practitioners and as the sport grows, the more information is needed to do well in tournaments. But just because it takes you that long to earn rank and win tournaments does not mean you are learning skills to protect you in a real fight. Ryan Young from Kama Jiu Jitsu spoke about this in one of his videos when he said:
"I was at an a event where Rickson Gracie was teaching and there was a black belt that didn't know how to do a basic headlock escape. He asked me if I could help him. Yes, I thought how is he the same rank as me and he doesn't know this? But I never said anything other than 'let me show you the basic one first and then I'll help you with the new one.' It was not his fault, it was his teacher's, and probably his teacher's."