If the coop is dry, which is best, the composting process can't proceed.
Deep bedding works by drying out the poop so that the bacteria that cause odor and issues can't grow. Deep litter works through the composting reaction where the good bacteria and other composting organisms react to digest the poop and the litter together and turn them into compost. This requires moisture -- not sogginess, but moisture -- and does best with direct ground contact because the necessary composting bacteria and organisms are in the soil.