Clearthink,
If you are going to troll me, which appears to be what you are doing, then you better sharpen your pencil or your Google skills, or go back to school.
1) Polypropylene is the second most common material used for indoor carpets and dominates by a large measure in commercial applications. Note my wording "often". The most common residential indoor material is Nylon.
2) Weave is a somewhat generic term meaning interlacing. A Berber carpet weaves a loop into a backing but does not cut it. A cut pile carpet weaves a loop into the backing and then cuts it. In both cases, those loops are made from .... wait for it ... interlaced (weaved) threads.
Your comment w.r.t weave is pedantic, inaccurate, and most importantly missed the point w.r.t. dielectrics / dielectric constants. As the weave of both the threads themselves are open (not tight), and ditto for the overall construction, most of the carpet ends up being air. This would be similar to the foamed construction of dielectrics in commercial cables. Being essentially air, the dielectric constant of the carpet will be much lower than the raw material used in it .. akin to those fancy dielectrics (like teflon) used in audio cables.
3) Porcelain has a much higher dielectric constant than most plastics. That is not remotely debatable. Also not debatable is that purely for an insulator of high voltage, dielectric strength is the critical measure, not dielectric constant. However, where a porcelain insulator is concerned, that is still not the critical measure, since the "insulation" is really not the porcelain itself, except where it is mounted, but the distance formed by the surface of the insulator between the wire and what it is being insulated from. That is why those insulators are usually wavy to increase surface length, or in technical parlance, creepage distance. Porcelain is used because it is strong/stiff, does not break down under sunlight (like most plastics), does not oxidize, relatively impervious to environmental contaminants, smooth surface is self cleaning, is non hydroscopic, and has all those properties while also being very cheap.