That's the point, you don't. You have to do what YOU think is important. Maybe that is important to them, maybe it isn't. The benefit to Stanford, Harvard, Princeton, etc, is that they are presented with an application that outlays a profile more closely resembling the real you. Of course, only the school itself will know what they are looking for in prospective students.

This is actually good, as it severely restricts the number of avenues available to prospective students, (and their parents), to game the system. And you better believe that students, and especially their parents, will try to game the system at a minimum. Again, many go beyond that with out and out attempts at fraud and cheating.