I am not suggesting that, in an encryption-free world, the advantage for the public is in being able to inspect all government traffic. Rather, it makes it easier for whistleblowers to bypass the government protections and get relevant documents that cover some atrocities.

I really like Assange's essay on the topic, where he describes that every big operation requires a sort of paper or document trail (which is used to coordinate many people), and this fact makes whistleblowing always an option.

However, I believe, encryption (and related things like trusted computing) helps to minimize the exposure of this trail even to internal actors, and in doing so, it makes whistleblowing more difficult.