In short, yes it does. Because adding the skirting to reduce moisture is counterproductive if it adds more moisture by not being vented. So make sure that the moisture can escape and that the air can circulate underneath the home.
You can add vents to the mobile home skirting yourself but most of the time, if you hire someone, they will vent it for you at no extra cost. Vents are cheap and can be placed periodically over skirting.