That's a different question. You asked how many people would have been harmed if weaker/no encryption was the standard. The USPS is a message system where federal employees are able to intercept suspicious content, and there is no built-in encryption for mail. Voting by mail is a great example of how a critical message can be sent without relying on encryption. Whistleblowers can still encrypt documents on a flash drive, and drop it into a mailbox. There is nothing stopping them from doing so.