I haven't read MacMillan, but I have read a number of books by David Fromkin, who broadly makes the same point that the interwar years should more accurately be read as a ceasefire. Specifically, his book A Peace to End All Peace is a look at how badly they fucked the Mideast in the negotiations to carve up the Ottoman Empire. Really fascinating how badly they fucked the aftermath of the war in basically all aspects.
Problem is the "Ottoman Empire" wasn't so much the "Ottoman Empire" as the "Ottoman periphery" and these lovely "modern" nation-states couldn't really fathom any organizational structure other than what they themselves had so why not divide up what you know between the Hashemites and the Qajars. It's always amused me that the UAE got a better deal than the rest of the Middle East combined simply because the British understood piracy better than tribalism. As for the powers-that-be they were busy worrying about becoming Windsors instead of Saxe-Coburg Gothas and not in the slightest about air power, chemical weapons and mass media. Cue Japan, who went "if we don't put down the kimonos and pick up rifles we're fucking extinct" but since no one on the Pacific Rim had any Saxe-Coburg Gothas, nobody took them seriously until it was way the fuck too late.