Normalcy bias.
Rhetoric and talking tough, alongside the wearisome act of carrying an unused big stick, leads to complacency and belief in the unassailable power of words. Why expend the energy and suffer the inconvenience of maintaining armed readiness when sternly-worded letters have kept the peace?
Eventually a generation arises without memory of use of arms, having only faith in words.
About that time, the evil recognize the unwillingness of the mediocre to fight, and return to the law of the jungle - while the mediocre inhibit the good, equating defensive force with evil.
correct