you make an interesting point and it reminds me of a counter point: that modern wars might have higher death tolls than historical wars, but modern wars - with modern weapons - end up costing less life overall compared to the populations of the time.
for tribal conflict of humans past, victory could mean wiping out the other tribe - 50% death toll or higher. as weapons advanced and more efficient and more destructive tactics emerged, wars can be more violent and more deadly but shorter and with fewer deaths compared to the overall population. wars became efficient.
all this is to say that if we didn’t have modern weapons there would be more killing - not less. “victory” would necessitate more deaths.
thank you!!