With EQ2, it isn’t really a big deal since most mobs are not social. However, using the waypoint system is a tool to find out how a mob with path to your group when aggro’d. Use invisibility/sneak to stand where the mob is, then use the waypoint tool to pick a member in your group. Watch the wisp trail that is generated, this is the same pathing engine that is used by the mob AI. So whatever path you see is how the mob will travel to your group.
Try it in places where the mob seems to get lost and then find its way back. You’ll see that the initial path is bugged to go the wrong way, the same path the mob took. If you follow it until it redraws, you can finally get an answer to why some mobs get crazy. It can also help predict what will happen when you aggro a mob.