Did the Ancients use their healing devices only to heal injuries, or did they also use them to cure diseases? Did they use them to extend their lifespans and youthspans, like the Goa'uld used their sarcophagus? If so, did they not have the flaws that the Goa'uld sarcophagus has (like making its Ancient user insane or only allowing the person to extend their life for tens of thousands of years instead of indefinitly)? If the Ancients had decided to create a healing device that would be safe for humans (or Goa'uld) to use in order to allow such beings to live indefinitly, could they have built such a device? Could a de-ascended Ancient like Merlin have created a perfected healing device? Could an ascended Ancient do so? If the ascended Ancients chose to (or were allowed to) interfer in the non-ascended world, could they use their power to extend non-Ascended beings lifespans, youthspans, and health spans indefinitly? Why didn't the Ori make their followers immortal in the non-ascended world so they could live indefinitely as worshiping batteries that never died and never needed to be replaced?