Well, let's try this: which agency, the NSA or the Stasi, does the following describe:
* Keeps records of who talks to whom
* Knows personal details of most citizens' lives
* Monitors the personal, business, and political communications of large numbers of citizens
* Operates in secrecy
* Has the cooperation of the nation's industry
* Collects more information that it can possibly process
* Claims to be working to protect the public
No, the NSA is not kidnapping people; that's the CIA's job. The NSA is a signals intelligence service. The Stasi's signals intelligence/surveillance system is what is relevant to conversations about the NSA, and there is nothing wrong or stretched about the comparison. Where the Stasi had informants, the NSA has Facebook. Where the Stasi had wiretaps, the NSA has room 641A.