Earlier quoted context omitted.
Close to the top of the article: > Between the lines: While the numbers are down this year, that's probably because many U.S. embassies and consulates remain closed for COVID-19, and taking this grave step requires taking an oath in front of a State Department officer. So it seems these are American passport holders who already live in foreign countries, so contributing to American infrastructure, etc, but not benefi…
They would not be EU citizens. The taxes are even higher. The article is around specifically renouncing American citizenships. Also, dual-citizenship is useless. If you are, say, in Russia, and you have your Russian passport on you, the American consulate won't lift a finger - your ass is wholly Moscow's.
Yes, true about local passports, but if I have a German and American passport in Russia, I'd just call the German embassy. Or is it not good enough, America number 1, Germany number 8?[1] BTW in your (correct) scenario, what's the point of owning the American passport?
On the topic of taxes, most countries have tax treaties. If their tax level is 30% in Germany and 5% in the US, they can pay the 5% and fill in a paper for the German tax authorities, and the 5% is discounted.
Maybe they're just people who didn't want to finance an idiocracy with the biggest firepower in the world. But rah rah, 'Murica!