The msg in question im suggesting is "&bDo /opme for Worldedit." so that new players wont get confused when worldedit doesn't work.
While i do forsee that this could possibly increase the intensity of griefs made by new players, it could help in player retention, as some players might leave after being confused at the lack of worldedit
another possible msg is "&bThis is Not Anarchy, Please read /Rules".
Image of what it could look like ingame. VVV
Another possible solution is to sudo them to do /opme and/or /rules at first join, although i advise against sudoing with /rules since it can flood one's chat.
Friendly reminder to keep debates civil and to not start any flame wars.