It's true that the BFST does produce some heat - however, that is not its main function. The BFST is designed to produce electromagnetic energy, and the heat you feel coming from the wrap is a byproduct of that energy. The warmth you feel from the BFST will not be as strong as what you would feel from a heating pad for a good reason - you'll typically feel warmth of a few degrees above body temperature.
Warmth or heat can lead to pain relief, but it can actually slow down the healing process. Heating pads tend to draw blood to pool nearer the surface of the skin, and that pooling blood can aggravate any existing inflammation. That's why the BFST is designed to produce less warmth. If you do use a traditional heating pad, it's best to use it for 10-15 minutes at a time.
The BFST uses electromagnetic energy to actually increase your blood flow and lead to healing the soft tissue. A regular heating pad can't actually help you to heal. The BFST provides all the pain relief that a heating pad would, and it works to heal the cause of that pain.