The name 'tortillon' comes from the French tortiller, meaning 'something twisted'. A tortillon is sometimes called a torchon. Torchon is actually French for cloth or dishrag, and a piece of rag or scrap fabric can be wrapped over a finger is often used to do the same blending job as a tortillon. Fabric fibers do behave differently though and a fingertip is less precise than a pointed tortillon! You can also wrap a piece of rag over a stick, knitting pin or q-tip.
Blending stumps tend to be used a bit too often in realist drawing. Because the paper fibers drag graphite across and into the surface of the paper, they create a fine but even layer of graphite with no white paper left to reflect light. This can make the surface very dull. It is useful when creating illusions of texture, such as velvet, but can easily make a drawing look lifeless. They are very useful when creating graduated highlights in textures such as hair, where the artist can blend, then sharpen the drawing with pencil line and erased highlights.