Ex Navy man here, and we have a couple of these hoists in the shop.

On lines in general, lines do abrade and it its the outer coating that does so. As mentioned, this fuzz may help reduce further damage. However, you do need to check that you have not gone completely through the outside sheath. All line degrades with time, and so replacing it every three years or so is desirable. These hoists do have a ratchet system which will contribute to fraying and wear. Other things that could degrade line is UV from direct sunlight (amazingly bad for nylon line), exposure to any solvents or salt water. If you use the hoists every day I would expect to replace lines every couple of years.