The Angels are voting, and Tyrael's finger slips and he presses the YES button, causing the Exterminatus of mankind. He feels really guilty, as humans produce the finest brews, the kind of brews that made him press that YES button in the first place.
However, the demons invading Sanctuary have caused the populace to stop making the kind of brews that are strong enough to cause Tyrael to be able to enter a drunken stupor. (This precise mixture was actually used by the populace of Sanctuary to melt down steel locks that they lost keys for.)
The demons begin to invade Sanctuary and fight Heaven at the same time, so the Exterminatus of mankind is put on hold while that ##!% with a spear fulfills his jollies by spearing everything in sight outside the gates of Heaven.
So he sends word down to Covetous Shen, because Shen is the Man, to buy the services of mages using gems made of the Essence of Tyrael, because some things money can't buy, but for everything else there are gems made out of the lightstuffs of the greatest Angel alive; who is obviously Tyrael, because that guy has got all the swag.
The mages under Tyrael's guidance, who can now think straight because of the lack of delicious brewskis, make the soulstones, and Tyrael coerces the heroes of Diablo 2 by hiding the keys to their house. "Dude, where's my keys?", a confused barbarian would ask.
"Dude, try Lut Gohlein, I swear I saw a bro take your keys, they had a skull keychain on them right?", Tyrael would reply in the form of Warriv, Jerhiv, Meshiv, and himself.
Because the lock-melting oil was no longer being produced, the barbarian had to go on and on in hopes that he could find the keys to the house he bought far away from Arreat, as he was afraid that the mountain would one day blow.
"That's hogwash," other barbarians would say, "The Ancients would never allow that!"
Convinced that the end boss of each act was the one who stole the keys to his beloved home, he drove fear into the hearts of the Evils, and they collectively noted him as "That crazy guy who killed everything in sight screaming 'Where are my damn keys!'."
Finally, the barbarian killed Baal, and much to his dissapointment, did not find the keys to his home.
Tyrael finally appeared, drunk as hell because the barbarians had a stock of the lock melting acid, and proudly announced, "You're a crazy bastard, sorry bro, here's your keys!", and threw the keys at the barbarian with all of his might.
The keys flew straight past the barbarian, missing him by about 25 yards, and smashed the Worldstone into pieces.
Realizing what he had done, he instantly went sober and flew to the barbarian, telling him, "Listen, Baal corrupted the Worldstone so I had to break it, if you tell ANYONE, ANYTHING ELSE, consider your home gone, and your family like... Dead or something! Also, here's your keys man, good work. I threw fake keys, made you worried eh?"
And thus, the barbarian was heralded a hero, and he quickly left to go to his home he bought near the Cathedral.