That ancient ball of yarn was almost certainly spliced, not drafted! You can see from the picture that it has a very low twist angle, and the little diagonal lines that show it is plied are quite far apart. So basically it was made by overlapping the long nettle fibres and twisting just enough that they hold together, then plying two strands together to stop it from falling apart when put under tension, like weaving. This ball looks like it may not have even been plied yet.
This method is faster than draft spinning and it results in a more even thread thickness, as there is little chance for slubs and thin spots as all the fibres are exactly aligned vertically.
Splicing is mostly associated with linen production in ancient Egypt but it is known in Europe up until the bronze age, when the introduction of wool made draft spinning much more common. The Must Farm textiles are another beautiful example of preserved vegetable fibres, with balls of yarn just as fine as this one!