Remember how Equestria Girls brought about Armageddon and singlehandedly destroyed the Brony community within the first few seconds of its first airing? How the blood of innocent ponies rained from the sky and stained the land of Equestria deep crimson? How chasms like titanic maws in the ground were torn open and swallowed the unsuspecting fans who dared to watch this movie whole? How the Four Horses of the Aponylypse rode forth to bring misery, famine, anger and death to any who survived? How the Princesses were struck down by the ultimate evil that is fully anthropomorphising anthropomorphic multicoloured miniature equines and how the entire planet imploded from the most dreaded cliche that was HIGH SCHOOL!?!?
Yeah, me neither
T'was a point at how many people were throwing shit-fits that Equestria Girls would be the end of the Bronies as we know it, but all the hostility was over nothing more than a movie that turned out to be pretty damn good; the destruction of the fanbase never happened and we're now partway through Season 4, hence why I followed up my comment with "Yeah, me neither"
As out of place as Sunset Shimmer turning into a demon was, the finale worked fine; mind you, the first appearence of Chrysalis when she removed her Cadance disguise in the Season 2 finale was a shock, so it's a welcome surprise when something so out of place appears in a cartoon like My Little Pony
I meant that the transformations were shocking considering this is My Little Pony, but yeah, I see where you're coming from; even with a full hour of animation for her plan to succeed, Sunset still got beaten and (possibly) reformed in four minutes while it took an episode and a third to get Chrysalis' plan to come to fruition and the rest was a badass fight scene topped off with the wedding ceremony
Plus Chrysalis had the first arc of the comics dedicated to her attempt at revenge on top of the Season 2 finale (even though the comics are considered non-canon, but still, it explains what happened to the Changelings when they were sent blasting off)