I understand that 24 hours news sites need to fill a lot of air time or that news web sites would like something new for you to look at each time you refresh but not everyone wants to follow the news as it happens and sort it out themselves.
Do you want to follow the balloon boy story, be fooled and then read about the sorted details as it unfolds... or maybe I just want to read about it a few days later wrapped (mostly) up.
Do you want to read the entire stream of new articles on digg.com when they have 0 diggs or do you only want to read them later when others have dugg them and you can read the cream of the crop?
Why do you read Slashdot? Because the quality of the articles and rated comments is higher than randomly surfing the internet.