It's important to have a diverse group of people asking and answering questions. If the diversity is so low that the site can't even attract a non-minority like women, that doesn't bode well for the quality of the community.
I think this is a wrong assumption. Qualitatively, it should be obvious that a diversity of perspectives and backgrounds would yield more answers. (Also a larger group of contributors can post more content to the site.) Empirically, multiple studies have shown that diverse groups are better at creative problem solving. Example: https://www.npr.org/templates/story/story.php?storyId=685821...
For example, one problem reported by the women that were asked about Stack Overflow was that one-upsmanship was an unpleasant theme. In what way could it be made less competitive without lowering the quality of the submissions?