This is true of champion competitors because they don't need to know anything other than what they do best!
Yes and no... Your comments bring up some very interesting and important issues.
You only need to "master" a few techniques. But you need to "know" the full repertoire. As they say, "Know your enemy."
The UFC was an eye-opener to the average martial artist who believed in the infallibility of his martial art. The Gracies and other grapplers did so well in the beginning not because BJJ and other arts are superior, but because they trained with and against their competition. The arrogance of the striking martial artists was their downfall.
Now everyone who steps into these rings is a "mixed martial artist," even if they only have a few techniques "mastered." Strikers are once again doing well, but only because people like Joey are ready, willing, and able to take it to the mat if that's the way the match goes.
- Bill