Mercy was remarkable because she was a woman and was still a successful writer. Mercy's family was strongly involved with patriotic politics which likely had an influence on her views.
Mercy shows women that just because you are a female does not mean you are worth any less or incapable of great things. She also shows that having determination can get things done regardless of obstacles that can be thrown in the way.
Mercy believed that women were just as powerful as men and despite critisim, she wrote what she wanted and became very influential because of it, but the criticism did likely man her second guess her actions.