Whats the common theme of what your stating? Either they were unaware of their injuries or they hid them from their team. In a professional fight BOTH fighters are checked for PCS and dilated pupils. I am sure a fighter would try to get away with it if they could but chances are they won't, especially with the athletic commissions checking up on fighters before, immediately after and shortly after a fight.
So, isn't that the point of what Dana White is saying? The UFC is stricly regulated, something like that can't and doesn't happen while it happens often in other sports. That was his whole argument, you seemed to miss the point.