I actually use the wicks to be able to start seeds directly in the plant cups in the NFT pipes or floating rafts for my Aquaponics system. Otherwise I would either need to start the seeds separately and transplant them or I would have to remember to top water all the time till the seedlings got big
enough to reach the water. With the wicks I save a huge amount of effort (transplanting tiny seedlings into cups of gravel is very tedious and many seedlings don't survive the treatment if you are not very careful and gentle.)
It will definitely work for planting seeds in small plant pots, just make sure the seed is touching the wick and that the wick material is able to lift the water far enough to keep the seed moist. (The rayon mop string is probably only good for lifting moisture 4-6 inches from the water source so it really only works for small pots not for huge ones.)
If you want to keep larger plants watered this way, use lots of strings and you only need to lift the water as high as the
roots of the big plant, not the surface of the dirt in the pot for the big plant.