"We didn’t hear the whole story during the Holocaust." (emphasis mine).

It seems meant in the sense of back then people weren't hearing about what was going on in near real time, and only afterwards was the full dimensions of the horror discovered.

Mind you, I don't think we are hearing the whole story of this Holocaust in near real time either: it's not for nothing that Israel has blown up the Hospitals (were the dead were counted), has murdered over 1000 journalists and is blocking them and aid organisations from entering Gaza - all of which stops people outside from discovering the full scope of what the Israelis are doing in Gaza.

We are hearing enough to know its a Genocide, but the full dimension of the thing (possibly with it, in scope and in methods used, already being or well on its way to be a new Holocaust - I mean, just look at how this piece from CNN unwittingly reveals how they're sistematically using buldozers to turn the appartment buildings they blew up into in situ mass graves for the victims, dead or even still alive) will only be discovered later if at all.