Board Thread:Quests and Special Events/@comment-5354013-20131210230220/@comment-20699994-20131213002340

SP probably chose not to put this event on both mobile devices and the pc to prevent users from 'double dipping' and claiming two rewards every day.

It would have made more sense to make this a pc event though. I'm guessing that there are more PC users without access to the mobile app, as opposed to the other way around.