I completely understand where you are coming from, but I'm not sure this would be a good idea. Whether a card is OP or not shouldn't be decided democratically, but by data and a strong understanding of the game as much as possible. Think about your average new player who has been playing for a week. Their vote would count just as much as an expert player.

GU Decks does list the win and play rates of the cards. Devs definitely reference those to get a general idea of card power. This is much better, as it's revealed information. Not opinions.