There is a fundamental failure to understand the purpose of a "veteran" being able to gank at a graveyard.
The game's content comes from the players.
You know that scripted event you see in 99% of other games? Where something happens, and you get your team together to fight it?
That is how this game works, but WITHOUT scripting. Players drive the events on this game.
If someone is killing people persistently at the graveyard, what happens? They give people purpose. You need your villains so your heroes have something to do.
You should be thanking that guy for having the initiative to create an event in the world. Do you not understand that? They ARE the content. They are the reason to get gear. They are the reason you're doing anything in the game at all. To build to a point where you can enact your will on the ingame world, whatever that may be; villainous, heroic or somewhere inbetween.
Don't like the guy killing people at the graveyard? Don't like people bullying the weak? Well, now you've got a reason to put your gear on and go defend them. You like bullying people? You like getting a rise out of people, or you just want to take their stuff to advance your own progress? Then you kill people at a graveyard. Maybe you are the weakling being bullied in the graveyard.. You have a choice to ask for help, and then they have the choice whether or not to help you or not.
The game is made in a way where constant moral dilemma's come up and you have to make choices. Why do you think the missions don't let you share the NPCs (Aside from the bosses, which is a shame, it'd be a bloodbath)? Because they want you to be confronted with a dilemma, in turn, this leads to potential events. The game is meticulously designed with this endgoal in mind. Player based events.
LOOK at the bigger picture. I swear, some people can't see the whole ecosystem at play in this game. You need people to do things like this in the graveyard. It is how the game creates it's events : via the players.