How to apply a gradient with the "Stroke-Visible-Paths" Plug-In?

[Ofnuts]

Because you asked path-inbetweener to generate a single path with several strokes, instead of several paths with one stroke each. stroke-fill-path with change the color from one path to another, not withing the same path (otherwise the 3D Gimp image above would have flat letters of different colors).

For the difference between a path and a stroke, see here.