The impact of feminism?

So, I just took a look at The Modern Library's 100 most important nonfiction books of the 1900s, and not a single one of them were on feminism (except possibly Virginia Woolf's A Room of One's Own) . None of the readers chose a book on this topic (And unfortunately seemed to focus on Ayn Rand and L. Ron Hubbard), and neither did any of the judges. This interests me because Professor Silliman once told the class that de Beauvoir's work was one of the most important books of the 1900s. As I contemplate the reason why, I can only come to two possible conclusions on why feminism is so overlooked: The first reason is that the equality, or at least perceived equality of the genders is so obvious to the majority of the individuals that they forget that feminism is a relatively new concept. The other reason I can think of is because of sexism in underestimating the impact feminist authors have made on society.