Yes, the sci.physics.research and sci.physics.strings forums are actually filled with posts automatically downloaded from the global bulletin board system called Usenet. The reason we disallow editing of posts to those groups is because the posts are actually sent off to the Usenet within about 10 minutes of being posted. There is no way for the poster to rescind the post, or edit it once it has been posted. The post will propagate to all the news servers in the world, and cannot be "undone."
Since we want physicsforums to present the exact same posts as those actually on Usenet servers, we cannot allow people to edit them after posting.
- Warren