Somewhat humorous example: In response to the need for warm clothing in the Korean War, US lawmakers instituted an alpaca subsidy in 1952. This subsidy remained in place for over 40 years.[1]
I do think there’s evidence that your second statement is true. Bad policy takes a lot of political will to overturn.
[1] https://books.google.com/books?id=fV_SuDMHpOsC&pg=PA273&lpg=...
Probably because you're only thinking about it from a US-centric POV.
As a Canadian who lives under a Westminster-style style system, there tends to be less gridlock here under majority governments.
I personally think it was deliberately put intended as a check/balance. Af the far end of spectrum, the most “efficient” form of government is a dictatorship. I’m not sure if what the US has is the correct balance, though.
When the party that made the "malevolent" change is kicked out, then whatever they did can be reverted very easily.
Contrast that with: if passing anything is hard, and a "malevolent" change does manage to be rammed through somehow (e.g., one party controls things for a two-year period), then reversing it will also be very difficult.