Head of the FBI and its predecessor from 1924 till 1972. So, for the US, we had a department "obsessed with finding and collecting dirt on their enemies with the intent to harm or influence them" for at least that time period.
Right, and Hoover's techniques were those of an authoritarian which few in Washington wished to support or tolerate. The problem was that Hoover's enemies included those very same Washington leaders, whom he'd quietly threaten.
By contrast, we've arrived at a point where those very same techniques, practiced openly and brazenly, are considered legitimate in the eyes of a significant plurality of both Washington leaders and the national electorate.
Corruption has always existed, but unless it's normalized you at least have a fighting change of containing it. When its normalized it will consume the whole system. Pervasive cynicism is sufficient to normalize it, and that's often how it metastasizes.