Probably an outgrowth of the "smash the Patriarchy, rawr girls are better than boys at all the things" brand of feminism. If so, then having a boy be front and center and speaking (for the purpose of this example) intelligently on a meaningful subject would have them lose their minds.

Or, and this is a pretty out-there theory, so feel free to pick it apart, they're trying to use the girls to the draw in the "yes, m'lady, as you say, m'lady" simps that always seem to hover around any issue that they think has a chance of getting them some pussy if they just front the cause hard enough.