Alas it this knowledge was hidden from the vast majority of people who rely on TV news for a long time. "Blow the lid off" doesn't mean the first person to reveal something, it refers to an explosion that can't be ignored. Kudos to the rest, but he was the one who really rang the gong.
Many revealed the Holocaust to the Allies during WWII, but very sadly, no-one managed "to blow the lid off" until Germany collapsed.
"The Nazis attempted to keep the Holocaust a secret, but in August 1942, Dr. Gerhart Riegner, the representative of the World Jewish Congress in Geneva, Switzerland, learned what was going on from a German source. Riegner asked American diplomats in Switzerland to inform Rabbi Stephen S. Wise, one of America’s most prominent Jewish leaders, of the mass murder plan. But the State Department, characteristically insensitive and influenced by anti-Semitism, decided not to inform Wise.
The rabbi nevertheless learned of Riegner’s terrible message from Jewish leaders in Great Britain. He immediately approached Under Secretary of State Sumner Welles, who asked Wise to keep the information confidential until the government had time to verify it. Wise agreed and it was not until November 1942 that Welles authorized the release of Riegner’s message.
Wise held a press conference on the evening of November 24, 1942. The next day’s New York Times reported his news on its tenth page. Throughout the rest of the war, the Times and most other newspapers failed to give prominent and extensive coverage to the Holocaust. During World War I, the American press had published reports of German atrocities that subsequently turned out to be false. As a result, journalists during World War II tended to approach atrocity reports with caution."
http://www.history.com/topics/world-war-ii/american-response...
So I thank Edward Snowden, even more than I thank the rest.