[itishappy]

> The bright red isn't just brighter, it's "redder than red"

You probably already know this, but there is such a thing as "the reddest red." A single wavelength of light is fully chromatic. As you mention, most color spaces use a "less red red," because it's easier to produce.

Some color spaces do use impossible primaries in order to capture more area but, as the name suggests, they are unphysical.

https://en.wikipedia.org/wiki/ProPhoto_RGB_color_space

Supersaturated colors do somewhat exist, but these rely on human visual oddities.

https://en.wikipedia.org/wiki/Impossible_color