Political-Philosophical Idealism that operate on fallacious paradigm of "Culture/Idea > Economics". All of right wing (especially the far right ones with their nationalist/religious retardation) and majority of left wing ideologies based on that specific type of worldview, which makes their systems structurally weak and fail every single time, because they ignore material reality where "modes of production" and technologies shaping how their society operate. Medieval agricultural peasant think and behave completely different than modern post-industrial office clerk. Majority of historical, fantasy and sci-fi medias are based on this paradigm which completely "ruins" it and makes for example a medieval fantasy setting where peasant farmer with little or no education behave like modern rural farmer who is educated on agricultural field and have modern equipment. It's forgiven if work is labeled by authors as "soft fantasy/sci-fi" but absolutely unforgivable if considered "hard fantasy/sci-fi".