Does questionable behavior need to be new and innovative not to get a pass?

The excuse I've seen innumerable times is basically: "This is nothing new - Entity XYZ did it, so what's your complaint?"

When did the dialectic enter the political discourse that not being the first to exhibit bad behavior gives one a solid defense? Or has it always been a fundamental part of human thinking?

(Note - I'm not accusing just DU'ers of this line of thought. It's pervasive on any discussion of current events.)