Rainbow Dash and Rarity could not be more different, and yet they are both girls. Rainbow Dash is not presented as wrong for being athletic and having no interest in fashion, nor is Rarity presented as wrong for being more stereotypically girly and interested in cats, clothes, and jewelry.
This was a revelation to me, as sad as that may be! Think of the variety of male presentations in those shows that have a Smurfette: little boys can watch them and learn to be a strong, silent leader, a brave hero, or a witty intellectual. Girls watch themselves be summarized down to a single word whose presentation might not fit. But in [My Little Pony: Friendship is Magic], there are a half-dozen main girls who are all distinct, all respected, and all work together after they move past the natural friction caused by their differences.
—World of Warcraft guildmaster and Glee fanfic author Miggy explains why Ponies aren’t just for Bronies.