I don't know how old Rick Perlstein is, but I can say Nixon's pathology more than anything Gerald Ford did was the catalyst for the distrust we have with our governmental institutions today.
Nixon was totally off in the head. There is nothing else that can describe this man based on what we know now. Think about it: WHO in his or her right mind would even THINK of putting his or her ambition above the good of the American people, of human lives at risk in a war thousands of miles away? This man operated on absolutely NO moral core whatsoever--Richard Nixon's cause was Richard Nixon, and nothing else. His ruthlessness destroyed the Republican Party forever--they now operate routinely on Nixon's utter lack of moral core in pursuit of power.
That may be his worst legacy, what he did to the Republican Party, but his crimes were bad enough. The man was absolutely beyond the pale, and what he would invariably do is claim "everybody else is doing it" to justify his own criminal actions. Obviously, not everybody else was "doing it."
We can look at the Nixon pardon 40 years later with hindsight and criticize it, but at the time it seemed to be the right thing to do given the fact the country was completely paralyzed by the Watergate scandal. Of course, we didn't know the entire story at all. Not even close.
It figures. A search shows Perlstein was born in 1969. He has NO clue whatsoever what it was like back then.