Ah. Good to know the explanation. I knew that they had changed the booking, but wasn't aware that it still didn't include the ability to book the entire stay at the first opportunity. I still think it's silly to have to call more than once for the same stay (unless some dates are taken, of course). One of the little foibles of the DVC that I've never really cared for.
As you can tell, I don't usually stay that long with our DVC. It's usually used for short weekend stays or Vero Beach jaunts.