LOL, actually, that would be pretty awesome.
However, uncontrolled events like this can cause complete chaos and make GMs very cranky. You see, Lord Kazzak had an enrage timer, after which he pretty much became invulnerable. And no leash. So once he got into the city and began obliterating everyone, he couldn't be killed and he wouldn't leave. So they had to do a server rollback. Plus, when word got out this happened, all the servers were suddenly trying it. It was like an epidemic of mass destruction. The previous video I linked showcases the kiting leadup more than the actual event.
This one much better displays the carnage.
Lord Kazzak was eventually taken out of the old world and moved to the Outlands, where he could no longer lay waste to the city.