Except in Tribunal when Eno Romari who was the leader of the end of times cult knew about the gates of Oblivion opening.
And lets not forget Caius Cosades:
When the emperor dies, nine hells are going to break loose.
Or Geilir the Mumbling's little friend, Oddfrid White-Lip:
When the dragon dies, the Empire dies. Where is the lost dragon's blood, the Empire's sire? And from the womb of the void, who shall stem the blood tide?
None of which made any sense until the story of Oblivion was made clear. Though Caius' made some sense, but made far more when taken literally, which no one did.