That is not entirely true. The U.S. does recognize dual citizenship, we don't really have much of a choice in the matter. If another country's laws says that a child born in the U.S. under certain circumstances is also a citizen of that country then there isn't anything we can do about it. We no more control their citizenship laws than they control our's.
A naturalized citizen cannot be a dual citizen in the U.S. because part of the citizenship oath requires the person to renounce any allegiance to any foreign country or foreign leader. And U.S. law also states that any adult who applies for and is granted citizenship in another country has forfited his citizenship in the U.S., natural-born or otherwise. If a natural born U.S. citizen willingly gives up their citizenship status then they can only become a citizen again through naturalization.
You are completely correct and I agree with you.
It is still a deliberate choice, and has to be such.