Part of the challenge of the League is for people to have to think a lot and if it is done "mistake proof" then this part of the challenge is lost.
I think that just like on anything, if you read the instructions carefully it is easy to prevent mistakes. People who skim read instructions often find themselves having to go back all the way for the same reasons.
Also consider that ND is doing a lot already, I dont think that asking the participants to pay attention aint that much at all.
Once again this is only my opinion and no harm intended at all.