A culture is set of behaviours which naturally mimetic humans copy in order to belong and enjoy the advantages of that culture. The higher up you go in status in that culture the more you will have to adhere to the values of that culture. Cultures, therefore, like any big group, act to leverage stupidity.
Any culture that encourages appearance of cleverness over real intelligence will create stupidity.
Any culture that encourages ignorance will create stupidity.
Any culture in which communication is poor and convoluted will create stupidity.
Any culture in which stupidity- when exposed- is the cause of demotion and ridicule will generate stupidity. Bizarrely, a culture that celebrates (without actively rewarding by rebranding it as something else) stupidity is one in which it probably won’t occur that much, as celebration heightens non-judgemental awareness- and being aware of stupidity and its prevalence is the first step to reducing it.
Any culture which force entanglement in big bureaucracies, big events, big groups of any kind will foster stupidity.