To understand the way it subverted traditional Disney princess tropes, you have to understand the tropes to begin with.
While many of those little girls have probably seen many a Disney classic princess movie, elements like that were really meant for the adults who had grown up with Disney and really understood the way things were changing.
While little girls were largely the reason that the original Frozen became a massive hit, and the reason we couldn’t stop hearing “Let it Go” for a solid year or more, it was still a movie that could appeal to broad audiences.