What you’re describing is real, but it actually supports the opposite conclusion in my opinion. Watergate, Iran-Contra, Vietnam, and the Pentagon Papers were exposed because institutions, media, and elites still broadly agreed that certain lines existed. Nixon resigned because his own party, the courts, and the press treated those constraints as non-negotiable. Reagan officials went to prison because enforcement still mattered.
Trump sits downstream of intervening decades of tolerated elite self-dealing, regulatory capture, and partisan blindness that have trained voters to believe that rules only ever apply selectively. When people see one side excuse its own violations for years, it lowers trust in the legitimacy of enforcement itself. Trump’s novelty is the abandoning of pretense.
Calling him a symptom doesn’t excuse norm violations, but it does explain why so many people are willing to tolerate them. The collective decision to lower standards didn’t begin with Trump; it culminated in him. Stress tests don’t create weaknesses, they reveal where faith in the system has already eroded. That erosion happened long before 2016.