The example gradient isn't supposed to be a representation of the spectrum, it's just smooth interpolation between three arbitrary colours. Have a look at the

The example gradient isn't supposed to be a representation of the spectrum, it's just smooth interpolation between three arbitrary colours. Have a look at the Oklab article I linked - the human perception of the brightness of the spectrum is very uneven. The point of this tool is to correct that unevenness, when interpolating between colours. Ultimately, CSS is really just about what looks good, so if you think one style of gradient looks aesthetically better than another, I can't argue with that.