Perceptual colors -- both sRGB and HSB -- are nonlinear, so you can't expect linear combinations to produce meaningful results (they often "interpolate through mud").

If you just want optical phenomena, you can just convert to luminescence -- WegGL and other modern graphics APIs actually does this internally when you load or render textures, so all shaders are handling optically-linear data, which is why the shader-produced images in the post look better than the javascript gradients.