Sometimes, when I'm browsing the Edited Guide, I think to myself, This article must have had an interesting time in Peer Review: I'd like to read the Peer Review conversation, and see what was said. (This applies especially to entries on particularly controversial topics, but all sorts of things might pique my interest.)
So I try the search function to see if I can find an unedited Entry on the same topic and read its conversation list. But many times the original Entry has been deleted or is hard to find. Hence the Peer Review Archive.
Below is a table laying out the Edited1 and Unedited versions of various Guide Entries. Even if the Unedited version has been deleted, its conversation list, which will include the Peer Review conversation, is still accessible.
The list is, of course, by no means complete. I'm working on it.