I find that laughable, when you consider that, depending on whose numbers you want to believe, anywhere from 80,000 to 250,000 people die every year due to mistakes, errors, $#@!ups and "medical misadventure" at the hands of the healthcare system.
In spite of that, people are "going to the doctor", in record numbers, with insane amounts of money being spent to do so.
I find it laughable because he said "preventable" care by accident. That's mostly what it is: preventable.
I do think that the entire way the system works could be revamped a million ways to the patient's advantage, one of which would be to consider those visits diagnostic in nature. Getting an MRI or a CAT for one reason or another is sometimes very important, but the "mother may I?" prerequisites coupled with the mandatory follow-ups are stupid. The same can be said for most blood or urine screenings. Let me know the results (which already have handy-dandy stars by them if they are out of nominal range) and let me move along.
As a short response to the OP premise, I would say stress and genes and environmental poisons.
You ask those REALLY old folks about their lives, and they are not counting calories or exercising to meet metrics. They exercise because their lives require movement. They are sharp because they still tell stories to their kids, grandkids, great-grandkids, and anyone who will listen (and they are usually from cultures that listen). They eat what they want, but most times what they have available to want in the first place is largely rather good, basic food. They are eating bacon and cheese in their old age, but that bacon isn't chemically-aided microwave bacon and that cheese is not "cheese food." They really aren't stressing about their cholesterol being high or low or whatever the latest thinking is. They laugh at all these people that are this damned worried about every microscopic part of their lives.
Genes have been altered by the environmental poisons we come into contact with but, beyond that, people who normally would not have kids are having them. I know a number of families like mine, where the grandparents had trouble coming up with viable children, but through repetition and the odds in general, they were able to have some eventually. Hospitals kept the mother from dying during the repeated attempts, or bleeding out during the pregnancies that did not end so well. The next generation had trouble, too, but now there were more monitors and experts and programs to help conception. By the time the next generation came around, the fact that genetic problems kept them from conceiving naturally was a laughable stumbling block, so long as insurance paid for it. The thing is, sometimes that difficulty in conception is due to other issues. There were a lot of little kinks and issues that were passed along to children who really would not exist otherwise. And that will be passed along through subsequent generations as well.
Environmental poisons are taking their toll, too, but not all of them are obvious or even acknowledged. Agent Orange claims are quietly piling up. Gulf War Syndrome isn't really talked about. At home, there were modern marvels in the form of plastics... that were not really safe. Changes to food, shortcuts for convenience, and the quickest possible ways to get food on the table so that both parents could work and then pretend they had "made" a meal equal to what they would have had if the ingredients had been clucking or in the ground a few days ago.
Just my $0.02