I think people confuse lack of qualified instructors with lack of information available to learn. Once you reach a certain point, the information you seek becomes very specialized, and therefore the number of instructors possessing and teaching this high-level information becomes exceedingly rare. For me, I've lately been focusing on the study of internal structure and manipulation. That type of material is very hard to find if you don't know what you're looking for in search of an instructor, but that doesn't mean it's not out there. Yes, there is the cliche that you can learn from everyone and it's true. I learn from my students on a regular basis. But in general, learning unique information and material is hard to come by, even across various styles and systems. How can this be?
So when you have been studying the arts for a significant length of time, it does not take you years or decades to pick up new information like it would a beginner. This is how people achieve high ranks in multiple arts, because they're not starting every single art at white belt and working their way up one belt at a time, nor should they have to. Especially when you are transitioning between similar systems, you are merely studying variations of what you already know instead of learning something new entirely so it only makes sense that you would be brought into that system at a higher level and progress faster than someone with no prior experience. That being said, don't confuse a paper chase with the journey of seeking new information or having a wide range of knowledge. Just because you learn a different system or style and earn ranking in it does not mean you are truly learning new information, even if it's presented in a way you haven't seen before.
But what if your desire for new information transcends what is readily available through your system or those similar to it? As a karateka, is learning countless new kata and their respective applications truly learning new and unique information or is it merely compounding on principles you already know? I once heard of a karatedo instructor being described as "the most knowledgeable martial artist alive" because he knew over 100 empty hand kata, with their application as well as numerous Okinawan weapons. To me that's specialized information, staying within the confines of Okinawan systems. It's no easy feat to memorize over 100 kata and learn how to properly use multiple weapons efficiently, don't get me wrong, but is the accumulation of multiple patterns of repeating techniques simply packaged in a different order really the accumulation of more knowledge? In my opinion, it's a smoke screen to give the appearance of depth and advanced information without actually possessing said depth.
When I talk about learning new material, I mean something that is truly unique from anything I've learned previously. Looking at it from the perspective of these high ranking instructors who have reached this plateau: if everyone can strike, throw and manipulate joints, I want to learn something not everyone can do. I want to be taught something that I've never seen before, that leaves me completely dumbfounded, not just a variation or another pre-arranged set of movements using techniques I've already learned. Which is why for me personally, I've been studying internals. Internal structure and manipulation is unlike anything else offered in the martial arts community, and it's also the most controversial (but that's an article for another day). I also plan to expand my teachings of pressure points, as well as the healing arts.
Unlike external arts that teach strikes, throws and joint manipulation, the information I'm personally seeking cannot be taught by just anyone, so I get it. It's frustrating to look at the martial arts community and want to train, want to learn and be stuck. But the information is out there! In order to find it, you need to drop the ego that we all develop, step outside of your comfort zones and the confines of your system, be prepared to feel like a beginner again and train. When people ask me what art I study, I always laugh because the art is irrelevant. I am student of Budo, and will learn from anyone who has information to share. That's how it's supposed to be. Regardless of what ranks, titles and licenses I earn, I will always be a student. If we don't continually seek new information, then eventually the truly unique information will die off and all martial arts will become a cookie-cutter, generic distortion of what it should be. The process has already begun with the evolution of sport karate and mega schools. So not just for our personal journeys of Budo, but for the betterment of the entire martial arts community, it's our responsibility as martial artists to continue learning and seeking new information, even if we have to turn over every rock and span the globe to find it.