That's very true. They wouldn't treat a urinary tract infection that my sister had, but they'd give her drugs to make her sleep. While she was still fairly alert, they were having a hard time putting a catheter in her, because she was fighting it. They asked me what I thought they should do. I told them to give her something to knock her out. They did, and they were able to insert the catheter without any problem. She never knew it was in her. Why I had to be the one to tell them that is beyond me.
It sounds like tbey were effectively asking your permission as close kin, to take this invasive step at sustaining her life a little longer.