The article is flat out wrong. The reason purple and violet look similar is not a trick of the brain, and has nothing to do with the color wheel "wrapping around"; it's a natural result of the frequency response curves of the three types of cones in our eyes. The two colors stimulate our cones in the same way, so of course they naturally look similar.
Most diagrams of our cone frequency responses are subtly wrong. Diagrams typically show three separate smooth, overlapping peaks, centered around red, green, and blue. What they leave out is that our L-cones (the "red" cones) also have a separate little sensitivity bump way off in the violet end of the spectrum. So when you see violet light, it's actually stimulating both the cones that are most sensitive to red light and the ones that are sensitive to blue light. This is pretty much the same stimulation pattern you get if you send both pure red and blue light into your eyes together, which is why purple and violet look so similar.
If you Google "cone sensitivity diagram" you'll mostly find the misleading versions of the diagrams, but you can see one that includes the extra bit of high-frequency L-cone sensitivity in this paper, for example: https://hal.science/hal-01565649/file/Vienot_ConeFundamental...
Most diagrams of our cone frequency responses are subtly wrong. Diagrams typically show three separate smooth, overlapping peaks, centered around red, green, and blue. What they leave out is that our L-cones (the "red" cones) also have a separate little sensitivity bump way off in the violet end of the spectrum. So when you see violet light, it's actually stimulating both the cones that are most sensitive to red light and the ones that are sensitive to blue light. This is pretty much the same stimulation pattern you get if you send both pure red and blue light into your eyes together, which is why purple and violet look so similar.
If you Google "cone sensitivity diagram" you'll mostly find the misleading versions of the diagrams, but you can see one that includes the extra bit of high-frequency L-cone sensitivity in this paper, for example: https://hal.science/hal-01565649/file/Vienot_ConeFundamental...