I agree with Dana on this, fighters can spot dangers better than people who haven't fought.
A few weeks ago, I had the honor of training with Rhalan Gracie, son of Relson Gracie, and grandson of the late Helio Gracie. Rhalan and the guy who runs Relson Gracie BJJ of San Antonio, Josh Lauber, said to only compete in BJJ tournaments where they don't allow really dangerous things like heel hooks, leg bars, and wrist locks.
In particular, they also said to make sure the refs have at least a brown belt themselves so they know how to properly spot danger. Unfortunately for Mr. Lauber, he had to learn it the hard way of getting his shoulder popped due to a ref who wasn't in the proper position to see the danger and see the tap.
The same could definitely be said for MMA.