I believe that was indeed their point. People used to dismiss mass surveillance of the US on its people as a crackpot conspiracy theory, until the full extent of it was revealed by Snowden.
Some conspiracy theories turn out to be true. Just a handful though.
By "people" you mean "some people" and there are always some people. For as long as I've been alive the predominant public opinion has been that mass surveillance does take place. We've had evidence for that decades before Snowden got specific about the NSA's abilities.
Not a great example since we know for a fact that mass surveillance is happening. The U.S. Congress just voted to extend and expand it.