in oral cultures people just re-adjust their memory, subconsciously[1]
in written culture, people burn books, driven by their leaders.[2]
in transitional cultures, 'bad' comments are donwvoted, or moderated away, or the users get shadowbanned[2]
[1] "Orality and Literacy" by Walter J. Ong, An american jesuit monk and academic.
[2] I made this up just now
[3] my highschool history teacher taught me this
[4] arguably, [1] also says this