Why do they do it? What benefit does their mission statement provide to that organization, and to the public?
Do you read the mission statements of the organizations you patronize? If not, why not? If so, do you believe them, and do you hold them accountable to living up to their mission statements? What purpose does the mission statement serve?
Can you personally benefit from having your own mission statement? If not, why not? If so, in what ways, and in what context (personally or professionally)?