i'm compelled to point out how much more effective she was than discord: he was starting to bore HIMSELF, and the worst he did was change gravity (but not enough to hurt anypony) she, by contrast, hypnotized the sole shield of canterlot, used his energy to defeat their pseudo-god, and led an army of (stormtrooper quality) changelings to feast upon the feelings of love, hoping to suckle the fat of the land until it was no more.
yup. so the moral of the story iiiis: the writers screwed up. they had to resort to saying "this works because we said it does", rather than keeping within the rules. because within the rules, chrysalis wins.