There's something to be said for rules and policy being adapted to a locale. What's right for people in one region might not work for some in another. You'll get a tyranny of the majority in much of your life the broader you go away from local governance. I agree there's benefit to have federal and international rules and policy but it's more nuanced than just saying sentiments for keeping power at a national level are fascist.

Nationalism is very specific to the modern era. It didn't really exist before the French Revolution. So no.

Unless that was a typo and you mean to write "after the modern era"