The main complaint about microfiber applicators is the that they absorb too much product. Over the past few years, as expensive coatings have taken over the industry, the complain has only grown. Microfiber applicators make coating product application easier, quicker and more efficient, but coatings typically have a lower viscosity (not as thick - flow easier) so they soak through the microfiber to the sponge, wasting valuable product.
There is an added layer of a hydrophobic material between the microfiber and sponge. This prevents excess coating product from soaking through the microfiber into the car wash sponge. It also limits excess product buildup which can become gummy and tacky as the coating begins to cure.