Researchers realized during WW2 that labor shortages left farmers in need of hands. They found that built up litter wasn't causing all the problems as previously thought. This gave way to the popular belief that built up litter, or what the popular coined term of "deep litter method" used today, was beneficial. The dietary effect of built up litter is caused by Vitamin B-12 that builds up in the litter. This is a side effect of bacterial action. Meat proteins have plenty of B-12 whereas plant proteins don't. In 1950, when B-12 was recognized, feed mills began adding it to poultry rations. They still do to this day, which is why built up litter, or "deep litter method" serves no purpose. One could say anti-coccidial properties might develop after 6 months when microorganisms develop that prey on coccidia. This may be true, but inconsistent since it invites all sorts of other problems to plague chickens. Namely mites, lice, perfect atmosphere for the ovation of parasitic worm eggs, darkling beetles which are a vector for tapeworms, ammonia, etc. Not worth the labor saving foundation of reasoning in my opinion. Raising chickens and keeping them healthy is not for the lazy, nor the stingy.
If one wants a compost pile, keep it out of the coop and at the opposite end of the pasture with a tarp to break it down. If you think spreading DE will right the wrong of using compost on the floor of your coop, you will soon realize all the scratching they do causes DE particles to be airborne and bad for the chicken's respiratory system.