This is my understanding also. In my view, applying through Questbridge is a major advantage, if you qualify. Not only is it a guaranteed 4-year full scholarship, but you have the advantage of essentially applying to 12 schools ED simultaneously, whereas everyone else has to pick one. Good advice to be smart about your list and your preferred order of matches.
I interviewed a QB student this year whom I liked very much. When I saw her application was withdrawn after the ED round, I sent her a note. She did not match at my school which had been her first choice, but matched at another top school. She was very happy.