People can then post said coupons and contests to FB, where they can interact with each other, using Facebook, instead of Brand X's website.
Why does Brand X need the interaction to happen on their site? It's not like FB is some magical land of coupons and contests that could not have been offered before.
EDIT: Also, why on earth do 300,000 people like a TOILET PAPER page? Is TP really THAT incredible? What business value comes from 300K likes on FB?