If someone can win let him win, I'd say and don't restrict him for all of these events.
I also hosted several metris events and so far noone got a higher score... But I still take part in those 
But I think it's ok if someone wins something like a cart event (happened a few times already) we announced before that the winner will not take place in the next race in the ranking. Means, he was able to drive the race but if he won the 2nd place got the 1st one and the 3rd the 2nd one and so on.
That's what events should be about,
FUN. Not only items..