"I hate to defend a man, but..."

More and more I've been seeing these types of comments online. Where a woman says or does something so egregious, that people are like "I hate to defend a man, but you are being ridiculous" or some version of that.

My issue is that women saying this apparently think women are so infallible, that they have to do or say something absolutely terrible to make someone be willing to admit that men can be right sometimes.

It's such an absurd concept to me. Like is it that hard to be open minded about a situation and not have your mind made up simply by the sex of the people?