These shoes have the effect of raising the horse's heels which mechanically makes sense - in a static horse, raising the heels shortens the DDFT. There is an extreme example shown here.
Once moving, the effect of wedged heels is that the horse is effectively walking "uphill" at every step - and if you watch any normal horse walking on a slope, going uphill will make it land more toe first and going down hill will make it land more heel first.
Of course, horses with DDFT/navicular pathology always prefer to walk up hill than down hill, because the back of the hoof is the area which is painful for them.
So on the face of it, wedged shoes are a good idea because they allow the horse to walk toe first all the time...Except that we know that a toe first landing causes undue strain on soft tissue over time, including on the DDFT itself.
There is also the huge problem that landing toe first does not allow the horse any real ability to shock absorb, as there is simply nothing which can fulfil this function in the toe, so every stride on hard ground will jar the limb.
A wedged heel is therefore a way of alleviating caudal pain for the short term, but it doesn't provide a solution. In fact, as these types of shoes don't allow the DDFT to fully extend, they can be problematic if used for too long.
Interestingly, Denoix and Pailloux recommend stretching the DDFT as an important part of rehabilitation, and this involves lowering the heel, and raising the toe to fully extend the DDFT.