Do you have a single ounce of data regarding the ratio of genders on Medium? Do you have any data related to quality of content created by the genders on Medium? Without that we cant begin to know where the problem lies. Medium may not (and likely doesn’t) represent the normal population where I would more than expect to find a gender balanced group of quality writers. It may not be “systemic bias” issue, but instead a writer acquisition issue related to no bias whatsoever.