These predictions about “quality of life” can be really inaccurate. It reminds me of many stories I’ve seen of parents with children with disabilities who are told by doctors that the child will never sit up, use his hands, or walk, and has no intelligence either, so should be put in an institution. Many times these predictions are too dire, and even if the child is very disabled, many parents want the child to remain with the family, where the child is almost always better off assuming a decent standard of living, loving relationships and good care.
However I think there is another extreme where people fight illness too hard when it is hopeless and maybe some doctors react to that. My uncle had gastric cancer which has a terrible prognosis but he did not want to give up b/c he was only 60 when he died. He had 14 rounds of chemotherapy and was in a great deal of pain, not able to eat, drink, or speak much the last 6 months of his life, and looked like he had aged 20 years when he died. He would have been better off with less chemotherapy and more medicine for pain. I don’t know what to say except maybe some doctors see cases like this and they may start encouraging people to let go in general, which I don’t think they should do. everyone is individual.