The dessicant can remove moisture from the air to slow down how waterlogged the filament gets, but it cannot reverse that and cannot dry the filament, and so the moisture level in the filament will gradually increase. A dryer will heat the filament to force the water out of it by evaporation.
You may feel the dessicant is sufficent, and it might be if you live in a dry region, use the filament quickly, and have a type that is more water-resistant, but I have to dry filament and find dessicant insufficient on its own.