The Alexandria Effect, or Alexandrian Effect, is a form of Knowledge Destruction, when someone or something intentionally causes information to accidentally get lost, on purpose.
It originates from the burning down of the library of Alexandria, to disperse information and culture in a way to prevent people from being able to correlate and understand factual truth, or history.
You: Dude, Why did the media pretend like they knew nothing about Hillary's e-mails, after they were publicly leaked?
Me: It's just the Alexandria effect.