The original documents, when they were still finishing the original Disney Vacation Club aka Old Key West, included wording about how people at other resorts if there were ever any other resort to be built could use the resort at Walt Disney World. All the other resorts were just a glimmer in someone's mind somewhere behind the scenes. My guess is that they expected "the other" resorts would primarily be off-site. I'm guessing that the success of BWV following OKW is what led them to continue to expand at WDW itself.