Could probably find it in Google but I think there was a study that show Harvard (and some other similar universities) do offer an advantage in that it's the only way many people from disadvantaged backgrounds can mingle with people with connections, opportunities, etc.,. There's no educational advantage necessarily, but the same students going to a state school for example aren't going to be exposed to the same level of access to upwards mobility. People that are born into families with that access however, experience no additional advantage since they were already essentially born with it.