"'White guilt' is predicated on slapping on a HUGE set of historical blinders and pretending that Europeans were the only ones that invaded anyone, or enslaved anyone, or ended cultures."

I deeply appreciate the dedication to historical balance, but I feel it's misplaced here. Your argument us literally predicated on Whataboutism?! which is the laziest and most dishonest way to hijack a debate. The fact that the Ottomans and Umayyads also engaged in slavery is irrelevant to the fact that Prince Harry is rich in large part due to the profits of slavery and oppression. 

But you're right, in a way;"white guilt" is a misnomer. Its origins in the (predominantly white) USA has led to an Amerocentric perspective which has clouded the base concept: that beneficiary descendants of groups of people who profited from slavery/oppression/etc. have corresponding expectations to be aware of their own history and to rectify the wrongs to the best of their abilities. That goes for ALL races.