One more reason why oblivion massacred lore
I wouldn't say massacre. Oblivion just seemed to disregard previous lore in favor of something that would add a crutch to OB weak plot. Some of the stuff that OB has given us is pretty good. If we were to go by OB's Dragonfire law, then during the Interregnum, daedra should have been walking about like it was no one's business. The only rational that can be applied is the fact that the Heart of Lorkhan was still chilling in Red Mountain, which allowed the barrier between Nirn and Oblivion to have enough strength to not need the Dragonfire's to be lit. But that seems like an escape hatch for the devs.