Mary Cassatt would not have been considered a controversial artist during her time.

This is not a true statement at all. Not only were female artists less accepted than male artists, but she joined with the Impressionists who were the radical painters of the day. Their style of painting was completely different than what was accepted by the art world at that time. Impressionism is considered the earliest form of modern art. Beloved today, but at the time was hated by many.