It's more that in the past widespread surveillance required a lot of people, many of whom will have a conscience which will end up disrupting your surveillance.

The movie Das Lieben der Anderen makes this point very cogently.

Nowadays you can run a huge surveillance program with far fewer people, all of whom can be conscience free.

Im not sure how the next stasi will crumble but it'll be a lot harder to wrest them from power with the tools they have at their fingertips.