I would consider the idea that a stone age society can't have advanced agriculture an insult to the stone age. The earliest culture to have any forged metalworking technology (as opposed to beaten softer metals) dates from around 2800 BC. Agriculture dates from about 10,500 BC, and urbanisation from around 7000 BC. Even paper pre-dates forged metalworking.
"Stone age" simply means no access to forged metal-working technology. It makes no comment on other technologies or concepts.
https://en.wikipedia.org/wiki/List_of_technologies
Even the idea that the Americas were stuck in the neolithic is wrong.
The Andean civilizations had extensive smelting of metals, including gold, silver, copper, and even arsenic bronze. It is true that metalworking was used mainly for adornment and ritual purposes, but this was beginning to change in the Inca Empire, which had begun making more knives and axes out of bronze. By 600 CE metalworking had spread to Central America, and by 800 CE Mesoamerica, where copper was widely used for bells, wire, pendants, and needles.
In North America, a separate tradition of cold-hammering native copper formed around the Great Lakes. Copper was more widely used in the region for utilitarian objects such as knives and fishhooks, but this may be because of the lack of empires in the region more than anything. Cold-working of copper also seems to have been independently discovered by some Alaskan tribes.
The Americas never developed a real bronze age for two reasons. One, they were just behind the Old World in terms of the foundation of agriculture, and hadn't had enough time. Two, there weren't large deposits of tin anywhere that the major copper cultures could utilize.