If you asked me back in 2009 if GTFO would become one of the most widely used, universally loved, and iconic addons in World of Warcraft's history, I would have laughed you out the door. You see, not standing in bad things was the ultimate test to see if you were ready for the big boy leagues. Sartharion and his three drakes brought a whole new meaning to the phrase "if you stand in the bad, you're losing DKP."
World of Warcraft made standing in stuff a staple game mechanic for boss fights and player spells and abilities. A common thread presents itself -- Blizzard took potentially clunky boss and game design and made it more accessible. Boss design used to be a mix of larger and stronger versions of regular mobs, like in the EverQuest planes, or unique mobs that would have some awesome new NPC abilities or even steal a player ability or two, like in the EverQuest planes. WoW might not have done it first, but the game sure did make it pretty and varied.
For every action, there is a reaction, and for every good thing to stand in, there are a hundred more bad things. Standing in bad things has become the joke of the era, culminating in Wrath of the Lich King with the ultimate send-off to positional and location-based mechanics -- heroic-mode Shadow Traps. GTFO's alarms and bells would echo down the sheer icy cliff walls of Arthas' monstrous fortress, the angry screams and painful sighs of adventurers falling to their deaths, the alarm not even finishing its full playback.