I believe that the principles upon which our system is built are indeed shared by many other systems. But the way in which we train to develop those principles as a driving power for our technique, and just how it manifests, is unique to our method.
So might not the manifestation of your principles be the thing that differentiates your style from the next?
How come it's not the method of fighting that distinguishes the fighting style?
The absence I mentioned in my post to Hoshin is precisely that: fighting.
I believe martial arts were created to encapsulate specific strategies that were then supported and ingrained through their training regimes.
You see this in boxing and MMA all the time. For all the talk of homogenising fighting with a boxing/muay Thai stand-up game, a wrestling game and a ground game, there have emerged not just fighters but champions, displaying unique fighting methods.
Compare Mohammed Ali to Mike Tyson (in his prime). One used footwork and distance to snipe his opponents before coming in for the kill. The other used body movement to evade everything while close up and bludgeon his opponents.
Their training differed because it was helping each of them be better at their specific fighting style, but ultimately faster tougher stronger is what training is about. Without the fighting style to guide their requirements their training would be the same.
I think Itosufication began the process of de-emphasising fighting methodology in karate, turning specialists of 3-5 Kata systems into 10-20 Kata generalists.
I think Bruce Lee put the nail in the coffin by popularizing the cool and pragmatic sounding "take whatever works" philosophy.
Whatever the cause, martial artists seem to place all their emphasis on the development phase rather than the execution. How we conduct ourselves in a fight; our route from conflict start to conflict end is in my view, what defines a fighting style.