I am not making arguments. I am speculating. No one we know on Azeroth seems to knew about the Titan stuff until we started digging things up. I mean if someone knew would it not be Azshara? Yet she did not know anything about the Legion, about Azeroth having a world soul or about the Old Gods. The Night Elves did not know about what was under Silithus or Northrend.
And when did Illidan travel the cosmos? He was imprisoned for ten thousand years. And then on Illidan he was using knowledge made available by rebel demons to access legion worlds and then blow them up, using a principle he personally saw in Outland. And then got imprisoned again.
I am just asking questions on how some things might work.