Had you read the article, you'd have noticed that this exact fact is noted and asserted to support the hypothesis:
> And then there is the case of the Incas, who oversaw an empire that grew both grain and potatoes. The Incas developed a way of freeze-drying potatoes by leaving them out at high elevations. This technology allowed them to treat potatoes like a grain: non-perishable, transportable and taxable.
The inca was only one of the major pre-modern root-growing groups, and the only one which had access to freeze-drying conditions.
"In the Altiplano, potatoes provided the principal energy source for the Inca Empire, its predecessors, and its Spanish successor. In Bolivia and Peru above 10,000 feet altitude, tubers exposed to the cold night air turned into chuño; when kept in permanently frozen underground storehouses, chuño can be stored for years with no loss of nutritional value."
https://en.wikipedia.org/wiki/History_of_the_potato
Seems like the potato was more of a blessing than a curse.