One, this barely touches on the opposite side, when doctors give up too soon. When my mom had a brain tumor that had a high 5-year mortality rate but still had plenty of time left, a number of doctors we encountered either gave us premature "time to give up" speeches or were just lackadaisical about treating her symptoms. (None of those doctors were her neuro-oncologist, and my mom was a fighter who would not give up on the time left to her.) Had I and my brother not been there to push back on the medical system, we would have had months less with her. Should we minimize the suffering when there's no hope? Definitely. But not until that point unless the patient clearly chooses otherwise.
Two, I think the much bigger problem on either side is not doctor attitudes, but cultural attitudes towards death. It's something a lot of Americans avoid talking about, avoid thinking about. My mom was a fighter, but because she had run an adult foster care home with an elderly wing, she was was also a realist. She had a DNR on file and we had all talked about what we wanted years before she got sick. We knew she wanted as much of a good life as possible, and then she wanted to be done. So when the neuro-oncologist said we couldn't do any more, that was it, and we transitioned to hospice. But from what I understand, that's not the common reaction. I hear stories from friends of dying patients dragged through all sorts of unwanted treatment because the adult children of the patient are unable to deal with their emotions enough to honor the patient's wishes, tend to the patient's needs.
So I ask everybody to talk with your family about what you each want. One framework I've used is Five Wishes, which has forms you fill out and material to help a family discussion along:
https://en.wikipedia.org/wiki/Five_Wishes
https://www.fivewishes.org/for-myself/
This is the most important thing you can do to minimize overtreatment: talk about it with family and get something written down. That way when the doctor turns to you and asks what the patient wants, you can answer with confidence.