Question about "Date Added"

I have a question about sorting by "Date Added." Noodlesoft says in their FAQ:
http://www.noodlesoft.com/faq.php#U5
However, if that is the case, how come a basic install of Leopard knows about Date Added, and lets you choose that sort mechanism in a the dock/stacks?
See screenshot:
Right now I am using Hazel and it's labeling downloads with colors to help me differentiate between new/not so new/old. I am also running a Folder Action to "touch" files as they are added to the folder (so modification date is updated.) Lastly, I created a Smart Folder to show me "Today's Downloads."
But it'd be a lot easier if Hazel and Leopard could cooperate on the built-in "Date Added" thing. And why doesn't Apple have "Date Added" as an available choice in Leopard's standard "View Options?" Just all seems so odd to me.
Date Added" is not an attribute recorded by OS X so Hazel records it itself.
http://www.noodlesoft.com/faq.php#U5
However, if that is the case, how come a basic install of Leopard knows about Date Added, and lets you choose that sort mechanism in a the dock/stacks?
See screenshot:

Right now I am using Hazel and it's labeling downloads with colors to help me differentiate between new/not so new/old. I am also running a Folder Action to "touch" files as they are added to the folder (so modification date is updated.) Lastly, I created a Smart Folder to show me "Today's Downloads."
But it'd be a lot easier if Hazel and Leopard could cooperate on the built-in "Date Added" thing. And why doesn't Apple have "Date Added" as an available choice in Leopard's standard "View Options?" Just all seems so odd to me.