I was talking with a doctor friend of mine. She told me that she had a new patient, a 75 year old man. She asked him if he had any medical problems, or took any meds. He said no. She was very impressed by his great health. Then she asked how often he saw a doctor. Hadn't seen one in 20 years.
Not sure what the point of your expression is. He was in good health because of things completely and utterly unrelated to visiting a doctor. If he had health problems, he'd simply die without seeing a doctor, which happens all the time.
Him surviving to 75 is utterly and completely irrelevant much like gay people being visibly present has absolutely no relevance to their literal existance. Gay people exist with or without being allowed to express, and health issues exist with or without being diagnosed.
"If you don't look for it, you'll never see it" is an extremely weird conclusion to arrive at from a story where there was literally nothing to observe.
If you don't see doctors, how do you know if you're in good health?
High blood pressure, coronary artery disease, diabetes, osteoporosis, colon cancer, etc are often called "silent killers". That 75 year old is "perfectly fine" and "in great health" until he falls, breaks his hip and dies, or has a heart attack and dies.
What going to a doctor does is open that guy's eyes to the fact that he isn't in as good of health as he thought he was. Just like how the world isn't as straight as conservatives thought.
It's entirely possible that if he saw doctors regularly he could have lived to 95, but because he was silently in poor health at 75, he "unexpectedly" dies at 76.