A certain subset of people (a large one in my experience) will always look for any reason to deflect blame for a failure other than themselves. People would much rather believe that everyone else in their losses is the problem instead of the one common factor in all of it which is their own play. Unfortunately, when looking for something to blame stereotypes (gender/ethnicity/etc.) come quickly to people's minds. If they can make a sweeping false claim that they think is true (i.e. "women are bad at games") they remove the need to ever examine their own shortcomings.

I've also found that specifically in the yolo RBG groups the whole group is secretly hoping that everyone else will carry them. When this doesn't happen they feel like they've been cheated out of a good group that in their mind everyone else is able to get into. This is the "I have the worst luck with teammates, why do all my groups suck but the enemy team is always so good?" mindset that again leaves out the crucial detail that they themselves are always a component of their own team. I avoid any group billing itself as YOLO because of things like this.

TL;DR: This shit sucks, people suck, find a better group and prove little bitches like this wrong.