In the Victorian period, women writers did not enjoy the same status as the men who wrote during that era. Works by women were considered frivolous and were not taken seriously. It's likely that most women were discouraged from trying to publish, either by their families or their friends. They may have also had a hard time finding a publisher who would publish their works.
Today, a writer might choose to write under a pseudonym if writing about a controversial topic. Or, if a writer writes for more than one genre, it may be easier to write under different names to build a stronger association or name recognition with each genre. (PLATO ANSWER)