A long blog post explains why the author, a feminist, is not comfortable with the rationalist community despite thinking it is "super cool and interesting". It's directed specifically at Yvain, but it's probably general enough to be of some interest here.
http://apophemi.wordpress.com/2014/01/04/why-im-not-on-the-rationalist-masterlist/
I'm not sure if I can summarize this fairly but the main thrust seems to be that we are overly willing to entertain offensive/taboo/hurtful ideas and this drives off many types of people. Here's a quote:
In other words, prizing discourse without limitations (I tried to find a convenient analogy for said limitations and failed. Fenders? Safety belts?) will result in an environment in which people are more comfortable speaking the more social privilege they hold.
The author perceives a link between LW type open discourse and danger to minority groups. I'm not sure whether that's true or not. Take race. Many LWers are willing to entertain ideas about the existence and possible importance of average group differences in psychological traits. So, maybe LWers are racists. But they're racists who continually obsess over optimizing their philanthropic contributions to African charities. So, maybe not racists in a dangerous way?
An overly rosy view, perhaps, and I don't want to deny the reality of the blogger's experience. Clearly, the person is intelligent and attracted to some aspects of LW discourse while turned off by other aspects.
Any community that claims to be based on 'rationality' runs an extremely high risk of inappropriately automatically labeling opposing arguments to their in-group assessment as irrational and dismissing them as irrelevant. They themselves are inevitably irrational and will make the mistake.
All of us have biases; that's something that's part of how the human brain works and simply cannot be avoided. The approach taken on LessWrong is not to purge oneself of biases, but to identify these biases and then consciously attempt to work around them in some way. It is implicit in this mindset that one will always have biases whose existence may not even be known. As long as everyone agrees with this, I don't think the community would devolve to that level.
The person who wrote this article has taken the first step - she's admitted to having a lot of biases that prevent her from accepting arguments that oppose her viewpoints. I'd like to see her take the next.