While those are not really Artist`s tools by themselves, knowledge of how to use them well may be a very important tool, not only for fractal artists but for everybody.
Finding the right color combo for your fractals may be pretty tricky, and the coloring can affect the final artwork a lot, sometimes changing it's whole appearance drastically. It is why some color theory info can be a very important tool for fractal artists. Of course it is not a universal rule, but rather a guideline, and will definitely help you to come up with pleasant and meaningful color combinations more easily.
You may read a bit more about it here:
And an awesome, yet underused,