From a cultural perspective, the NA server is more individualistic and thus the ones who speak out in chat will often dictate how long a raid goes. If information on the fight is being delivered and morale high, a raid will very likely continue. If nobody speaks up after a wipe, than likely the morale is low the raid might collapse.

As for loot, if you really want pieces for a set, just speaking up about it will increase the chances of your party letting you have it. Otherwise everyone gets a shot at loot to do whatever they please with it.