This is called griefing, its not pvp, its abusing. All new players will just quit, because a. low area are not playable, because of damn bots (which most high graders roll), and better farm places are constantly and obsessively abused by high graders pk characters.
Also what gm's could do is extend the blessing of protection for people to level 76 but remove the "x levels difference" and also make it stay for a longer period, say 4/6/8h. i find a spot, you go like 30 min there and then after 30 min farm u have to go back to town to get the blessing again.
Also, why can pk chars be su