Especially some of the actual practices surrounding it - I've had some really bad experiences with e.g. the Less Wrong crowd tending towards assuming there is no value to human emotion, and so failing to even make a basic attempt of integrating into a community rather than dominating it with debate-is-the-only-form-of-conversation, attacks on people's identities under the guise of "you asked a question, that means you want me to tear you apart", and more.