Idunno, seems like more cultural cheerleading than defined fact finding. I'd guess American uni's do well because 1) we control the publications doing more of the ranking, 2) we've got more money, 3) the mentality is less restrictive in exploring new ideas than say some of the prominent European schools. Of course high demands create some luxuries too. I can name some possible benefits to a diverse campus (I noticed this at the time), but I can't really say that's what made them "great", though if you're part of the diversity cohort, certainly that's better than simply being shut out.

And the diversity bit on military - again, a wish hoping for a justification. I don't recall homogenous Japanese and German and Russian armies being too slovenly or ineffective. Consider the Russians made it all the way from Moscow and Volgograd to Berlin - 2800km - in the time it took us to cross the channel and move a third the distance. And then we've been stuck in Afghanistan since 2001 with our supposedly uber-effective diverse forces trying to train the natives to take over for us - fat chance. Vietnam went well, right? How long & how much effort did it take to defeat ISIS sitting open out in the desert?