Lets say I upload an image, then click add full size image to post. Later I edit the post and delete the attachment file, then save post again. The post has not auto removed the full-size image I inserted into it. When an attachment is removed it should also auto remove it from post as well if inserted into it, like inserting a full-size image.
I just did exactly that with this image below. Deleted the attachment and not the full sized inserted image link. Many people are going to delete attachments and not bother also removing the full-sized image of it inserted in the post. So it should be auto done thing removing it from posts like phpBB does it I used before to avoid broken attachment links left behind in posts