Anything which relies on external hardware to run, such as MMOs and other Live Service games, are by necessity left to the vagaries of things happening outside of your control. Even worse, things can happen that were outside the control of the developers too. All the recovery plans, redundancies, and contingencies in the world mean jack diddly if something happens which bypasses or wasn't covered by them occurs. When a person chooses to play an MMO, they are choosing to depend on factors they have zero control over in order to play the game. But you know what? Getting angry about something going wrong doesn't solve anything. Nether does demanding people who are already working tirelessly to fix the issue to be "held accountable".
Know what I find interesting? I can think off several MMOs off the top of my head which also regularly suffer from severe lag. Among them, Age of Conan can suffer from severe lag spikes. As can Everquest 1 and a few others. The interesting part to me is that the games are almost all ones which were originally coded for Windows XP, thus coded for underlying PC architecture which modern Windows does not use. They also are games that never updated the game's base code to the point where the game no longer supports XP and (potentially) Vista. This suggests to me it's not that the servers or network hardware is out of date and causing lag, but that the game's trying to run on modern hardware that struggles to run games designed for Windows XP.
Other games that have similar slow-down issues include single player games like Spore, Knights of the Old Republic, Clive Barker's Undying (this one struggles on Vista too), Prince of Persia: Warrior Within, and Bloodrayne 2. And that's in addition to graphical glitches and clipping geometry issues caused by old XP games trying to run on a modern Windows OS.