Not saying they're faultless, but as long as the well of eternity existed, somebody outside was gonna take notice. The elves just happened to be there at the time (and quite possibly were already heavily corrupted by the presence thereof)
UPDATE: Poll will close on May 5th, at which point the Faction will be chosen based on highest votes. Currently The Horde is winning 8 to 5 with 50% of the votes.
Poll closed on Sunday, Horde wins with 52% of the votes. The Skjaldborg will be rolling Horde for Classic.