In the BC (Before Computers) era, if one wanted perfect privacy, they would remember things and not write them down. They would talk to each other in their own homes with security from government eavesdropping about ideas, politics, anything they felt like. The fifth amendment gave them the right to keep such things from government "oversight."
Now, there is more to remember and machines to help us do so. Should these modern aids help the individual or make the jobs of surveillance agencies easier?
Put another way, would anyone want their careless/drunk/drugged/lusty words used against them in a courtroom?