Regarding miniature rope, not thread, each has advantages and disadvantages.  Rope made from organic line tends to stretch/sag with time and environmental conditions.  For PE the biggest disadvantage to me is that it needs to be sealed where a cut is to be made as it will unravel otherwise.   Organic rope is friendly with diluted PVA to secure a splice or seizing.  CA glue seems to be a favorite for PE but it leaves the spot hard and brittle and often discolored. There are likely other plusses and minuses and  I am anxious to hear other opinions.  I recall hearing of line made from combined materials that seemed to work very well for making miniature rope.
Allan