History is written by people who actually write shit down. The whole "written by the victor's" nonsense is mostly for dumb arguments about politics.

Tons of sweeping generalizations or understanding of the past exist because that's literally all that survived from that time that was actually recorded.

Most of the history of Africa is completely lost cause basically no one wrote anything down. And the only history we have comes from the people who invaded countries on the coasts and recorded what they were told.

An actual good use for the phrase is probably for the fuedalistic period in China. So many empires were started and ended over a short period of time. And so little is known about the time cause the people coming in would actively destroy any recorded history. China's whole history is plagued with that practice. That's what the cultural revolution was all about. Burning as much of the past as possible that might prevent the unification of China and cementing their new power.