politics

Physics is the absolute worst with this, too. When I was doing my postdoc in a climate lab, by far the greatest amount of pushback against climate science as a discipline (at least internally) came from the physics department. They sometimes think that since physics is in some sense the "most fundamental" science, they have a right to pontificate on anything else since everything is, at bottom, a physical system. Combined with the fact that they deal with mathematically sophisticated but frequently highly idealized or constrained models--and thus are skeptical of complexity in general--this sometimes gives them the attitude that they can pick up any other discipline and do it better than genuine experts. It's a pretty pervasive problem.