But would you trust math olympiad performance over good grades in graduate level math courses? What about publications in respected math journals? If by the time you graduate from college your math olympiad scores are the best things you have going for you, you've got a problem.
But it takes more than a scalar score on a test to prove your ability to integrate whats around you into something new. If you get a perfect score on one of those tests and don't do jack shit afterwards, what does it mean?