There's still possibilities for a legal draft to be initiated. If the United States officially declared war on someone with congressional approval (something they haven't done since world war 2 I believe) if millions upon millions of workers/soldiers are needed, they would be drafted.

Life is very unpredictable, especially world events, so there must be frameworks always available to manage the draft if it's randomly instituted at some random point in time. Therefore, you need a standing office of running these frameworks in preparation for anytime. And in today's digital world, nearly everyone or thing has a Twitter account, including government bodies.