That is not accurate. I made one this past December 6 months prior to visiting. They gave me a reservation number and confirmed my information upon arrival.
I will try WDW dine - I know how to do the downtown Disney one - you definitely can call them directly - I just wasn't sure about the DAK. I know the service and food are fairly basic, but it's a tradition to go there during the trip and my kids will be thrilled just to get those darn rainbow slushies!