Like how Cata's changing of the loot system made it possible for 10 mans to get the same loot but leaving 15 others from they're 25 group behind, Discord, websites like openraid that schedule raids and likely "cross realm" have destroyed Guild raiding. I mean if you ask me it kinda removes the thrill of getting together, taking time out of your busy week to down some hard bosses. I'm just saying.
