Postulate (Sturgeon’s Law): 90% of everything is crud.
Observation: Part of being educated in a field is learning how to filter out the crud produced in it—the work which is slapdash, too banal to spend brain-time on, fundamentally misguided, boring. This “learning how to filter” includes both recognizing bad work quickly when one sees it and taking advantage of existing social mechanisms for winnowing intellectual wheat from chaff.
Result: When Alice, trained in one field (say, physics) looks over into another (e.g., philosophy), she’s likely to hit crud. If this happens a few times over, Alice is apt to form a low opinion of the other field, a low opinion which is in a way justifiable but which in a deeper sense is misleading. This process repeats with Bob, Carol, etc.; by the time we get to Xenia, there is a notion afloat in one field that the other isn’t much good, leading to reciprocal enmity from the other.
Observation 2: If Amelie is formally trained in one field (say, pure mathematics) and accomplishes something legitimate in another (perhaps she pens an evocative new translation of the poems of Ryōkan), then the fact that she jumped discliplinary boundaries will be less remarked upon than if her effort failed. The departmental affiliation of a competent worker is easily forgotten, but that of a grandiose blowhard is easily remembered.
Overall result: In a subtle way, the world gets worse.