He doesn't blame the pad for a sore back, as the pad can't make up for the saddle. I have seen wither sores that take three or four years to heal. One horse developed a bone infection from wither sores. For the horse's legs, wraps intend to support and protect. Sports boots are designed to distribute impact.
Some models aim to add support.
Any boots or wraps should permit the leg to stretch. If fastened too tightly, the pressure can irritate the leg. If fastened too loosely, they can slip and bind. If you wrap your horse's leg with a tight bandage, you might see inflammation when you remove the bandage. The compression of the tendon is caused by wrapping too tightly, or pulling the bandage unevenly while spiraling it over the tendon.