Use of the game term "Time-out" implicity suggests to the child a percieved lack of seriousness on the parents part.
Time-outs are an ineffective form of discipline, especially with young children. They need something immediate and unpleasant. Being sent to a bedroom full of toys or being put into a corner for five minutes is not unpleasant. And if the only consequence that the child suffers for leaving the time-out area is to be taken back to it, that quickly turns into a game that takes up the parent's time without teaching the child anything.