I did say rarely, and if you are looking more carefully a pluralistic democracy wasn't really what a lot of the founders were after, especially guys like Jefferson. Sure we're happy we got it, but it wasn't necessarily the aim and we got SUPER LUCKY that Washington decided to step down and retire. The former military leaders of revolutions almost never do that.
And I think you have that backwards. The nonviolence movements of the mid to late 20th century are the exception more than the rule when it comes to achieving change.