it’s as valid IN ENGLISH to use it to refer to the country as it is to refer to the continent(s)

It's really not but you already know that, just as you know the (s) is incorrect because, in English, there is absolutely no such thing as a continent called America.

It’s not about confusion, it’s about the US acting like the center of the fucking universe.

It's about you being a hypocrite and accusing a group of people of acting like the center of the universe because they use a word differently in their language than you use it in yours. You are being incredibly disrespectful of other cultures by trying to impose foreign definitions on how people describes themselves.