any bronie that says that twilight is a mary-sue now never got the point of the show in the first place and they were never truly into the show. a strong character like her with her powerful magic advancing in her place in society based on her hard work is not a self insert, shes exactly what you want kids to look up to.
look kids, she didn’t get this spot because shes rich or because shes related to them or because her mommy and daddy did it for her, she got to become a princess because she worked hard and studied and became a powerful unicorn all of her own hard work. if you work hard at your own special skills you could become the top of your field too, just like twilight.
thats not a mary sue, thats giving little girls and boys that watch this show hope to their dreams