People supporting their countries is not exactly radical.
Well from an anti-state perspective, supporting a country that commits radical acts such as monopoly of violence is by extension radical, but i think you meant that patriotism is widely spread, and that is relatively true, at least most people have patriotic "instincts" (even though in my experience, discussing and questioning their patriotism often reveals that they are patriotic by default and could have a different position if they reflected upon it).
it's very common everywhere but Lemmy because this place is filled with tankies.
I'd say tankies are also patriotic, just not for USA. Fatherland is a quite important concept in post-leninism forms of authoritarian communism. From my experience, it's much more common to find anti-patriotism in libertarian communism / anarchism than in despotic communism.
Repeating history being entirely compatible with patriotism, right ?