The main difference is that, should the would-be applicant flake out and never actually design his area, he hasn't wasted as much staff time. You can't "wash out" if you're never "in" in the first place.

Maybe there doesn't need to be any official apparatus in place to support this, and individual would-be staff members can just decide on their own whether to start work on an area beforehand or not. Speaking personally, I don't think I'd ever consider applying again unless I had something already partly designed. If for no other reason than to atone for the lack of effort the first time around.