When a field becomes detached from reality, society, the sciences, other arts, it becomes entirely self-referential.
What causes inbreeding anyways? What can be done to prevent it? Stop it? Reverse it?
I think the key is 'entirely self-referential'. Because every sufficiently advanced field becomes more or less self-referential earlier or later. This is due to the lifting of external references to self-standing definitions (in math, we have the extreme: axioms). In math, at least other fields refer to it and so establish a flow of 'use'. But if a field is neither used nor uses other field, it is really inbred. But I wouldn't claim that necessarily for the above fields in this extreme form. A better example might be pseudo-science.