References? In my personal experience that's far for accurate. If anything they are an extremely nationalistic country.

Living half way between the US and the EU has taught me otherwise - that the kind of cohesion between say Portugal and Sweden is surprisingly solid - once you know where to look e.g. social values, political views. Trying to do the same with someone from deep Texas and a little town in the Maine coast could be an interesting example of the opposite.

Having different languages even inside the same territory doesn't account for lack of cohesion. It's quite irrelevant in practice actually.

Cohesion seems to be mistaken these days by sheepishly following politicians into unnecessary wars and lacking critical thinking. Widespread ignorance is not cohesion, is divisive at best.