I would not consider it significant whether musicians are female or male either. But I do consider it significant that an all male band is considered "normal" ,but not an all female one . The fact that this thread exists surely suggests that there is a perception that an all woman band is unusual .I think that might put some women musicians off joining or forming an all female group .
For women gender is a selling point much more than it is for men . An all woman band would get talked about and get marketed as an all women band.I don't think that's right . But, while greatly admiring the bravery of those who refuse to let stereotypes interfere with what they want to do , I certainly wouldn't blame young women for not wanting to join an all female band.