If you had a huckster cart in Baltimore- this would be considered abuse and your horses would be seized.
Of course it’s one way of doing things- but I think that it really is a system intended for Northern Climates where composting outdoors has stalled- snow outside is deeper than the wheelbarrow wheel and pee on a thinly bedded stall floor would be a little mound of ice. The deep litter is a solution to many problems of winter- but I think that if you do this in warm climates the build up of ammonia- and the danger of things heating up in the barn make this inadvisable.