I've seen it time and time again. A person will join a Martial Art school and absorb tremendous amounts of knowledge for the first few years.They're hungry to learn and work their way up through the ranks and once they achieve "expert" status level,they go out & start schools of their own.What's happens a great many times at this point is the learning stops & the once eager,open-minded student starts to think they know it all or that their particular way of doing things is the best or only way even when presented with fairly obvious factual information to the contrary.They will close off their world of learning and continue to do the same things however irrelevant for the rest of their lives.They become fiercely loyal to a particular method or style(usually their first one) and refuse to consider other ways.
I think this phenomenon happens because people don't want to feel that that they may have wasted their time or they don't want to give up their position of authority that they feel they deserve and have worked so hard to get.I watched this happen in the 80's with "Dojo Wars" and this style vs that style arguments and it really came to a head when the UFC debuted in the early 90's as some people simply refused to open themselves up to what the UFC offered. Grappling which had always taken a back seat to the standup striking arts as being inferior was declared king by many in those early days and many jumped on the grappling bandwagon.But over the next few years as the striking arts was reformed and restructured,we quickly learned that grappling by itself had just as many limitations and much of the success of early UFC competitors was due to unfamiliarity with the grappling arts & it's techniques by exponents of the striking arts and that it was actually a holistic integrated approach that would ultimately prove to be most effective in the long term.
Ther Gracies who founded the UFC would eventual learn that their system was severely lacking and simply wasn't as relevant as it was in the beginning.Many conventional wisdom's proved to be fallible.If a grappler takes your back, it's over was often repeated in the early MMA contets,but then cam Sakarabu with a new style and introduced a variety of uses for the Kimura into the mix which are still integral in MMA today.Head Kicks once said to be all flash are now effective & common place in MMA.These concept of these lessons can be applied to all aspects of reality-based self-defense.Firearm technology ever advances,so it would make no sense to adhere to a platform that is inferior & outdated.Physical Unarmed techniques will not vary,change & develop as much as weapon technology and arms them weapons themselves,since the Human body doesn't really change all that much over time,but out understanding of how to achieve peak performance does ever increase with new scientific advancements.Unarmed fighting is very an Art that uses scientific principles,but there are so many variables to consider that it cannot be condensed down into a blueprint or formulae that can be predictive.So,you must ever be open minded and flexible in your thinking and mindset & therefore forever be a student.