The difference is, of course, the claim that blood is thicker than water has been a relatively reliable way of guessing where someone's loyalties lie for millenia; while the "response" is a cosmopolitan universalist tic common only to the past 70 years or so, and flying in the face of so much experience & common-sense requires shaming anyone who thinks otherwise.

I think you could make a better argument for nativism than "its been that way for millenia" and "it's common sense". Warring tribes were also around for millenia and were probably quite common sense.

Most people consider the modern state, society, etc, to be an improvement. Many people also consider not questioning people's loyalties by their surnames, to be an improvement, even though I'm sure it was common sense for a long time.