Some of the original 'plumbers' group was to stop real intel leaks. Recall the Democrat leaning guy who stole the "Pentagon Papers" and leaked them to the NYT? This was a crime similar to Snowden, and hurt the government. There were other leaks (Democrat politicians learning things in secret briefings, and then the info leaked/passed to Soviet operatives.
Yes - Nixon was guilty of helping a cover-up ...but was far less criminal than what has happened in the past 5 years - IRS abusing its power, NSA gathering data on citizens, Benghazi cover-up, etc.