There mass surveillance back then was child's play in comparison what is possible today. There is a tipping point which is hopefully still in the future, where dissent is detectable and predictable enough that regimes are no longer at risk to collapse.
If you look at collapses of authoritarian regimes due to public pressure, they happen to a similar pattern. A small group of people start a protest and depending on how hated the regime is and how bad the living condition for most people are, others will join in, the more the less likely it becomes for them to be individually picked out.
This only works if the initial small group has enough time to motivate enough people to join in so that it snowballs. Earlier approaches were to minimize the time the small groups had to snowball with quick and hard actions, but with more and more surveillance, it becomes possible to target people even before they join. At a certain point it becomes possible to watch over every last citizen and target anyone who might be willing to start something like this in the future.
If you look at collapses of authoritarian regimes due to public pressure, they happen to a similar pattern. A small group of people start a protest and depending on how hated the regime is and how bad the living condition for most people are, others will join in, the more the less likely it becomes for them to be individually picked out.
This only works if the initial small group has enough time to motivate enough people to join in so that it snowballs. Earlier approaches were to minimize the time the small groups had to snowball with quick and hard actions, but with more and more surveillance, it becomes possible to target people even before they join. At a certain point it becomes possible to watch over every last citizen and target anyone who might be willing to start something like this in the future.