I'd hazard a guess that it's the lowest common denominator midwit way of thinking. Exceptionally gifted people in my experience tend to have a greater variation of more detailed nuanced and sometimes even more eccentric views. Brian Donaldson, Penrose, Ramanujan, Planck, all great men and all eccentric in some way. The first creationist I ever met IRL was also someone with an IQ of over 135. Part of that is that highly intelligent people, outliers, have higher openess to new ideas and we know now that the genes for outlier high intelligence overlap with the genes for autism so there's some truth to the eccentric genius stereotype. Newton was an eccentric a-typical Christian and Einstein was a Spinozist.