What exactly has led to revisionist history?

Take for example muslim denials of the Islamic conquests, or of modern antisemitism (while being antisemitic 😂) or the wonders and generosity of the Ottoman Empire (while it conquers large swaths of land and massacres people) . We have a few here who love posting that nonsense from time to time.

Or the movement in the west that attempts to insert minority communities into western history? Take for example the 1619 project, black vikings, or other nonsense.

What exactly has led to revisionist history?
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