hi bb,
your "painfully obvious" makes a bit of a mush. there were countries that were attacked and therefore fought. and others that fought and were not attacked.
hitler invaded poland.
france and britain declared war on germany because it did so. they did so reluctantly because war is not the first alternative and everyone knew that Germany had a huge arms programme. so it was a scary thing to do.
the so-called appeasers were actually the same folks who drew the line in the sand and called it poland. hitler crossed it and in doing so misjudged (or perhaps was careless of) the will of british and french politicians. i think chamberlain's attempt to avoid war and establish a peace treaty was worth a try. i don't see what else he might have done.
i don't see america's avoidance of participation as a very high pulpit from which to abuse the folks who were actually trying to convince hitler to back down peaceably. appeasement. but also a line he was not to cross. when he crossed it, france and britain declared war.
the trick of the thing is not to assert that the us is the hero of the story, but just a hero. then no one is bothered. it's okay not to rewrite the story with the us as the central character and everyone else hopeless without us aid.
the war began in 1939. non-us folks feel slightly insulted by the us-heroic version of the story. hence the reminder. it's okay that the us was self-interested rather than filled with selfless compassion for the world. let the cause be pearl harbor.