This idea can work. They do it for Magic the Gathering using MTGO.
Magic has the MOCS - Magic Online Championship. To qualify, you need to earn enough points and if you make it, you get an invite to worlds to play it out at the event.
It doesn't stop cheating from happening, but MTGO has in the code of conduct that you agree to when you start using it, that only you can use your account. This has actually been policed in the past, very recently, when a player qualified for the MOCS, but was found to be playing on an account owned by his friend. I can't remember if the invite passed down of if the owner of the account got it...
Then once your at worlds, you play on rigs supplied by WoTC and have a judge present to ensure that everything is above board.
I don't know about you guys, but when ever I play a game and have someone trying to help behind me, my game goes to hell. What they see and what I have planned often conflict and that can cause me to loose sight of my original plan and make mistakes or poor choices...
But I agree with Flint, this idea, whilst it has merit, can not be and should not be implemented until PTCGO is stable and the card bugs ironed out.
Pope.