I think we're quickly approaching a slippery slope here. Seeing as a username is attached to every post, isn't the user somewhat responsible for every link (s)he posts? It now constitutes part of their reputation. Now, if an editor modifies the post but the username is still attached to the post and their is no indication that it's been edited , is the original poster still responsible for the post? (S)he can turn around and say, "That's not what I posted. I don't want that attached to my submission history. I don't want any karma that's associated with that altered post, whether good or bad."