Not this historian, thank you very much
Haven't these people ever heard of continuities and ongoing processes as matters for the historian's interest?
Historians are always keen to identify key turning points: decisions that significantly alter subsequent events.
In context, this seems much more about the desire of meedja types to find some pin to pivot their programmes on - if it's not 'new revelation!' or 'secrets uncovered!' it's 'turning-point of history!' This is possibly about perception of audience and reception and the perceived need to have some kind of USP.
I recommend those all purpose quotes with a view to 'Discuss, giving examples':
It was the best of times, it was the worst of times
The best lack all conviction, while the worst
Are full of passionate intensity*
Can't even summon up enough pshaw to headbang or codslap. (History - Ur doin it rong.)
*Or, as I rephrased this in lolspeak:
The Best: We used 2 have conviction: but we losted it
The Worst: All ur passionate intensity r belong to us.