True, but that's incredibly easy to translate to the PHH timeline, as the cause of fog given off by the Industrial Revolution and a lack of proper safety.
That isn't really the issue though. It doesn't matter that you can come up with a nonmagical explanation for the deaths that would be accepted in the time period, the real issue is that at least 10x more people died in these Singularity clusterfucks than the real life historical events that they warped.
A reminder of the death tolls from each Singularity:
-Fuyuki: An entire city of tens of thousands of people dies in 2004.
-Orleans: large swaths of the French countryside are depopulated, most notably Lyon and Orleans (and Paris? I forget) are completely fucking massacred, and King Charles died early.
-Septem: Relatively low-key for a Singularity since I don't remember large civilian populations getting massacred, but plenty of soldiers still died and considering it's the singularity second furthest in the past that should have a massive butterfly effect.
-Okeanos: Doesn't really matter since it was a bullshit patchwork realm and I don't think we had any confirmed real people aside from Francis Drake's crew, who mostly survived.
-London: The historical pollution fog that killed plenty of people was cranked up to 11 and then they just infested it with killer robots. Because fuck you that's why. The historical event killed thousands, this probably kicked that up an order of magnitude. And the Clocktower was completely wiped out.
-E Pluribus Unum: The only place we really get to see destroyed by the Celts was DC, which is bad enough, but they took control of the entire east coast and were massacring anyone they could find. In 1783 That's where literally everyone (aside from the natives) lived. Looking back on things I'm wondering how the fuck Alcatraz was a thing.
-Camelot: The Crusaders all died and most of the natives of Judea got massacred.
-Babylonia: Oldest human civilization that literally everyone on the planet is probably descended from is reduced from tens of thousands of people to 500. And you know, ends at least a thousand years early. Even if the tide that converted people into Lahmu doesn't count several cities of thousands of people still got obliterated before that.
How the fuck is the planet supposed to fudge any numbers to make important people still be born and all of history happen mostly the same when there aren't any numbers left to fudge? setting aside the butterfly effect for a moment, France and the US should've just stopped existing as nations with the casualties they suffered. Did the Akashic record just shrug it's shoulders and replace the dead with saberfaces?
In short, nothing makes any sense and the only logical explanation is that best Gilgamesh was fucking with us.