FWIW, publicly available poll results do largely prevent people from creating a ton of sockpuppet journals to vote for themselves, or voting from their RPG journals, etc. It would have been high suspect if several Draco Malfoys had voted for me!

It also means that the nominees don't really dispute the results and the awards can't be accused of being "fixed" for the friends of the organizers, etc. if all the votes are visible. That kind of drama has damaged other awards where the results weren't transparent.