Even shihans dont have eyes in the backs of their heads. Get the drop on someone, they're done. Armed, yudansha, military, cage fighter, power lifter, gangster, psychopath, all fall down with a 2x4 to the back of the bean.
Even if someone doesn't get the drop on, one good/lucky shot turns the tides.
true but you would hope somewhere down the road, especially if you've reached shihan status, that you'd be better equipped. You may never be able to perform a "perfect" technique in a real fight, but through the process of training surely you should be given some tools to help you know how to fight.