I think that the Democratic primary voters are reflecting what the media has told them. The media is chauvinist.
Also, is it possible that the media was embarrassed by having inaccurately predicted that Secretary Clinton was going to win, and that, rather than consider its failure to understand the public, has instead insisted that she didn't win because a woman can't win?
How did we get from "Secretary Clinton is guaranteed to win" to "Who can beat President Trump?" The media is so chauvinist that it simultaneously demonizes and deifies a male President, to make him seem all-powerful, rather than to concede that the media didn't know what it was talking about when it said that he was going to lose in 2016.
In 2008, a black President was overdue by a few hundred years. A female President is similarly overdue.