Twilight Sparkle was the first Element of Harmony to represent said element well wnough to become an alicorn. She accomplished magical feats unheard of by ponykind. She bested Starswirl the Bearded with an even stronger magic. Friendship. As Twilight learned many times, friendship is magic. Therefore, magic must be friendship, right? Twilight was the first pony to ever prove this wrong. If the theory were correct, she would've gained her wings and princess title when she first earned her cutie mark - thankfully the theory is not correct. She accomplished great feats of friendship, hence accomplishing even more magical feats.

Unbeknownst to Twilight, she had long exceeded the magical potential of Princess Celestia and Princess Luna. Indeed, Princess Twilight Sparkle was the most powerful pony in all of Equestria. So naturally, when it was time for her to sit in a throne and rule the land, it was incredibly easy. I only wish I was telling the truth.