Now imagine that happening once per generation for 3 or 4 generations in a row, followed by / contemporary with getting invaded by an alien army with significantly superior weapons and ships whose goal was total domination and enslavement / elimination.
So the general theory is that if you kill half of the population the descendants will be better off? What's the mechanism, and what happens if you follow that to its conclusion?
That's only about the black death, and some specific reasons for why that helped, kind of, _some_ parts of Europe. First, it definitely didn't help everyone - Norway, for example, lost all economic power and went into the 400 year night, as it's called (it was under Denmark). And secondly, it's a single case. You can't create a general rule from that. It's vastly different to compare that case to when e.g. 95% of the population died out in certain places during the Spanish conquest.
And, again, take that "rule" to its logical conclusion: How many people will inhabit the Earth after a while, and under what conditions will they live?
