Originally Posted by ubertuber

I think the distinction is that in the majority of MMA fights, the match is not over when someone is knocked down. The disadvantage is real, but it's not an unfair way to fight. I think you can tell that by the fact that hardly any fights end within 30 seconds of a fighter going down. In fact, many times, the downed fighter holds on until the uend of the round, or even rallys and wins the fight.

MMA refs make the distinction between "knocked down" and unable to fight. Of course you can quote some instances in which that didn't happen, but you'll be finding the exceptions rather than the rule -- and those exceptions become rarer all the time.