The 'New Post' feature wouldn't pick it up by default so no one would know it was added. Even if it was coded so it did, people would expect a new post, not an edited post. People would look at the end, not at the start. It's just against the work flow everyone is used to. And it would involve hacking up VB which makes future upgraded harder to do. It would also put all existing replies out of context. It would suddenly look like people have been replying with silly answers. It's against the threaded and chronological nature everybody is used to.