This is usually a sign that it wasn't the article's author who misunderstood ;)

Physically, people obviously could see the same frequencies. But what to make of the raw perception has a cultural aspect - after all, the whole band from 400 nm to 780 nm is continuous, and we are able to perceive the complete range[0], so the color categories we use have to be arbitrary to a degree. So seeing here means consciously differentiating, not physically perceiving.

Anecdote: I was working in a print shop during university. After a few years of consciously comparing small hue differences, I became almost offended if someone in class talked about a "purple" line in a graph that was clearly magenta to me. I couldn't care less a few years before.

[0] = many parts indirectly, though, e.g. yellow is not a color we can see directly with the cones alone, it is processed first.