I think the larger point is that along with he loss of so many lives (and the horrors of the Somme and Stalingrad and Buchenwald) came a loss of righteousness in Western Europe. Positivism was replaced by relativism. If our culture brought us to this, then what is our culture worth? It’s a fair question.
WWI was certainly a mess in that empires were won and lost,
traditional cultures were uprooted and changed, and the class system (love it or hate It it had it's reasons for being) was almost wiped out.
I think you could argue that even with a lack of a war such as the Great War, Europe would have changed anyway. With the rise of institutional Socialism in 1917, sooner of later Europe would have had to stand.
I agree with many people that in truth, WWI did not end in 1918, but more like 1945. Some would say that WWII actually ended the day the Berlin Wall came down.
Matters not really, what Europe became was due to many reasons, and most certainly lack of a true moral compass is telling to this day.
IMO, there will be another European war (isn't there always another one), but the next one will in no way resemble any we have seen before.