An Aikidoka could survive in a cage, but he would likely not win. A NHB fighter could escape a knife attack, but he would likely not have known how to defuse or avoid an attack altogether. Which is better?
Fighting in a cage is optional. Dealing with real life is not.
Also, I'd much rather describe the events in question as "mixed martial arts." It's pretty silly to call any event with a referee "no holds barred."