There is another advantage to ED especially for someone who is in target for the reaches. Eg at or about 75% for Penn Brown or Cornel but is not spectacular in any way by the standards of top colleges. If you are one of 6000 applying as opposed to one of 30000 there will not be as many just like you.
This means two things, you will only be the 10th violin playing, stem, debate team captain they have seen that day, as opposed to the 500th that week. Plus, you become part of who they are building the class around as opposed to someone used to fill in the class.