It is, in fact used as a dye for fabric. It's in many of my natural dye books.
Of course, the rule for anything that changes the colour of a fabric is that it does so best when dyeing or staining something that you want to remove the colour from. This is why blueberries produce a wretched grey dye on fabric, unless you drop them on your best white shirt, in which case the spot is bright purple and never fades.