It is true. Unless you're born in the United States, the only kind of US citizen you can be is a naturalized citizen, which is not a natural born citizen. It's right there in the Fourteenth Amendment. "All persons born or naturalized in the United States..." And Congress cannot amend the Constitution via simple legislation. The 14th amendment doesn't limit citizenship at birth to just those born in the US and subject to its jurisdiction, it just says that everyone born in the US or US territories and suject to the jurisdiction of the US is a US citizen. This meant that former slaves and children of slaves became citizens. Prior to the 14th amendment, slaves were living in the US under the jurisdiction of the US but were not citizens and had no rights as citizens of the states. The 14th amendment says nothing about the status of the children of US citizens born overseas.
The 14th amendment doesn't limit citizenship at birth to just those born in the US and subject to its jurisdiction...
It does exactly that.
All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States, and of the state wherein they reside.
It is quite clear that the the only US citizens there can be are those who are born in the United States, or who are naturalized in the United States. If you are not born in the United States, the only way you can be a US citizen is by naturalization.
The 14th amendment says nothing about the status of the children of US citizens born overseas.
The Fourteenth Amendment establishes who are citizens of the United States. If you are not a citizen under the Fourteenth Amendment, either by being born in the United States, or by being naturalized, you are simply not a citizen of the United States.