So, Guild Wars 2 has a lot of cliffs and high ledges in it. Really, a lot of them. Jumping up and climbing and platforming are a significant part of the experience. Unfortunately for players like me, unlike other games it has no safe fall skill you can train up. Falling equals falling damage and, often, falling death.
It also has, particularly in PvP, a bit of a mob rush mentality, for the moment. A wild event appears, and everyone chases it. Perhaps to their detriment (and to their demise).
In fact, the lemmings have more sense than to leap off a cliff unprompted. MMO players? Well, we'll do anything for a lark. So if anyone's mother asks, "Well if all of your friends jumped off a bridge, would you jump too?" the answer is apparently, "Well, if we're in GW2, then yes."