> Maybe you skipped over the "almost no one" aspect of that section you quoted.
Nope! These methods were available to everyone who was literate as well as anyone who either maintained oral traditions describing how to perform them or just decided to make up a language for fun. Maybe you're forgetting that our ancestors were generally just as smart as we are today.
> The original point was about scale and the scale (and strength) of encryption available today was not possible for most people until the advent of computers.
This is completely irrelevant. Why? Cops have access to computers that can brute-force most everyday ciphers that would have been cooked up in the 1700s. The just outcome is for non-cops to have access to those same computers to create and use ciphers that restore the ability to keep one's private communications safe from the eyes of the police back to what it was hundreds of years ago.
This just outcome is -incidentally- what we have today because of a lot of tireless, difficult, thankless, ongoing work by some absolute heroes starting most visibly in the 1990s and continuing through today.
As a bonus, none of this has anything to do with the establishment of dragnet surveillance systems built and operated by private companies that are defacto acting as agents of The State. Dragnet surveillance is -at minimum- plainly antisocial and has no place in any civil society.
EPN3D's point stands despite your complaints: the only reason that the illegality of these dragnet surveillance systems wasn't immediately obvious to the courts is because the US Constitution doesn't explicitly mention that courts must always consider the expanded scale of what enhanced technology makes possible, so courts are very slow to incorporate it into their decision making process. Judges and lawyers rely heavily on tradition, so this slowness is only natural.
You are arguing against no one. The "almost" indicated an admission it was possible. No one was accusing people in the past of being stupid. My point was about the practicality of it. Or to rephrase the same idea, what percentage of human communication do you think was encrypted in the 18th century compared to today?
That's why it works as an analogy to mass surveillance. Surveillance was always possible, but now it is scaled up so a much higher percentage of our activity is surveilled. The commonality is that computers made these two things much easier to do. The purpose of my comment was to show that's not inherently good or bad by showing one example of when that's viewed as good and another when it's viewed as bad.