I may just be blowing smoke,
but but it seems to me the ribs are self basting when cooked in a rack making for a more moist product. if you have a full rack of ribs I like to rotate the ones in the middle at some point in the cook and when I put them in the rack I make sure they are facing opposite of each other allowing more air space between them. If I were to foil which I don't, they would be laying flat and not in the rack after being foiled. Having said that I hate cleaning them even when sprayed down with pam before hand. If you need the space something that some do here is roll and pin them with wooden or metal sewers and set them on end, I have never done this but some people do and maybe they will chime in on that. The dishwasher is your friend with racks.