Have you ever heard a blond joke which was about a blond guy? I haven't. Blond jokes -- even if the target is just referred to as "a blond", are always about women.
So along with the discrimination and prejudice which women generally face, a woman who is blond has an additional layer to tend with. This is sometimes referred to as intersectionality -- when more than one type of discrimination or prejudice impacts a person. Another example of this is the experience of black women who are discriminated against based on both gender and race.