Another possibility is that among the many beliefs a person has, focusing on belief perfection is "over-fitting" (as we are always accumulating more knowledge),

Another possibility is that among the many beliefs a person has, focusing on belief perfection is "over-fitting" (as we are always accumulating more knowledge), and that some misfit beliefs just happen to be really socially detrimental despite that many kooky beliefs don't cause people to exercise violence or harm against their neighbors.