We don’t have the staff to review hundreds of posts self-edited by members long after posting to see if the edits were necessary or if they “gut” the content of the thread. Some members would go through and delete all of their posts, leaving gaps in many discussions. I’ve seen it happen, and it’s not pretty.
The other thing that happens with long edit windows is that the original poster (or an early poster) changes his/her post, and the subsequent replies no longer make sense.