User blog comment:TheFreddyFromThePizzaria/Equestria in Peril-The Legend of Princess Twilight-Part 8/@comment-26186871-20161018204607

Just here to clarify something: The reason why they didn't use use the Elements is because they didn't HAVE them. Way back in early Season 4 of the Show, which would be Part 3 or 4 of the legend, they gave up the elements back to the Tree of Harmony to prevent Eqeustria from falling into chaos.