There is something extremely irritating about a person who almost agrees with you, and yet refuses to accept everything you say. Sometimes you get angry about them more than about your enemies, whose existence you already learned to accept. At least, the enemies are compatible with the "us versus them" dichotomy, while the almost-allies make it feel like the "us" side is falling apart.
Upvoted for that.
In my experience, groups that want something to attack will attack groups that are generally aligned with them, rather than groups that are further away -- possibly due to the perceived threat of losing members to the similar group.
I've seen so many Communists get called Nazis by other Communist groups -- and those groups never go after people who actually call themselves Nazis.
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:
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.