Some thoughts.
err umm that's near impossible. Not only is it a way to sneak in stuff past the moderators post-facto, as Barb mentioned. It also means people can go back and revise or remove anything for any reason, on a whim.
Now if Xenforo is advanced enough to allow versioning (i.e. you would see the most recent version of a post and there would be a notification "there are x previous versions" and you could see them - that would be acceptable in terms of content management. But I don't think that exists.
In order to preserve conversations, forums usually only offer a short editing time window, that's normal.
The workload you would get would be unmanageable. I mean, I'm not a high frequency postr, but just to salvage my stuff, that would mean going through many of my posts in the witches thread, some posts spread out over other people's threads like
@Jollyrei's Death & Maiden, my entire soppy sentimental photostory thread etc. -- even if I prepared this perfectly "go to post
www.cruxforums.com/xf/threads/8280/#post-547257 and replace i.imgur.com/mHmo9ay.jpg with bottomlessp.it/312312.jpg" for each & every edit, it would probably be hours of work.
Now imagine doing that for all the active members using imgur...