False equivalency. The Black Death was not 100% infectious -- otherwise there would be a lot fewer European complexions in the world -- and would have responded to sensible measures for preventing infection like proper hygiene and identifying and blocking the vectors of transmission. (Also, the victims did not get back up after dying, or seek out infection in order to infect others.)

The zombie infection transcended the accepted rules of diseases in the game. Opening a box infects me with a disease that kills in minutes, and cannot be cured by even a level 70 paladin? The victim would probably not live long enough for the infection to spread effectively; at most, it would have killed everyone in Booty Bay and gone no further.

Regardless, I do not pay $15/month to take part in a real-world infection simulator. I signed up for a role-playing game, and I chose a PvE server because I don't grief other players and don't care to deal with people who do.

If you'd actually read my comment, you will see that I CHOSE to take part in the event, and did my best to kill as many zombies, both PC and NPC, as I could. (Especially the PCs, as nothing is quite as delicious as griefer tears.)

Blizzard broke some of their own rules in order to make the outbreak more "fun" (players not being able to reliably cure or avoid the disease, zombie PCs in Shattrath able to attack non-zombies PCs but non-zombies unable to attack zombies) and did not provide players who wanted to fight the outbreak with enough tools to do so.

It was a ham-handed railroad job that any seasoned DM in a tabletop roleplaying game would be embarrased to put their players through. Why did the plague vanish? It sure as hell wasn't anything I or any of the other players did to fight the zombies. The way the infection spread on my server, the only Alliance characters to survive the infection would have been the ones that were never played during the outbreak, which means Arthas would be facing the might of banking alts and battleground twinks.