fstop123 via Getty Images Caring, African descent home healthcare nurse conducts medical consultation with senior adult woman at her home or nursing home. The female patient is sitting in her comfortable chair while reviewing her medications information with her nurse or doctor. Backyard can be seen through the windows.

Should medicine be ageist? A young trainee doctor recently proposed to me that it should. Health care is overstretched, she argued. "We can't do everything for everyone, so why spend money on old people, who have little chance of benefit?" For her, ageism is not all that bad -- in fact, it's a practical response to limited resources.

I'm unpersuaded. Ageism is not benign. We fail older people when we treat them, as typically we do, in ways that are at odds with how ageing works. Ageism masks our need to do better.

The challenge is the complexity of ageing. With age, almost all diseases become more common.

Health care has gotten pretty good at treatment, assembling teams that specialize in specific problems. Kudos and full-page ads celebrate this focused, subspecialized care.

Here's the trick though: patients do best when their single illness, no matter how complicated, and no matter what their age, is their main problem. Subspecialized care may work very well for them.

The complexity of ageing arises because, as we age, we are more likely to have more than one illness and to take more than one medication. And as we age, the illnesses that we have are more likely to restrict how we live -- not just outright disability, but in our moving more slowly, or taking care in where we walk, or what we wear or where we go.

Not everyone of the same age has the same number of health problems. Those with the most health problems are frail. And when they are frail, they do worse. Often, those with frailty do worse because health care remains focused on single system illness. Our success with a single illness approach has biased us to think that this is the approach we should always take.

When frail people show up with all their health and social problems we see them as illegitimate - as unsuited for what we do.

So, would the young doctor be right if instead of restricting care in old people, she simply opted for restricting care for frail people? Should "frail-ism" be the new ageism?

For health care, such a notion would be self-defeating. If frail patients are unsuited to the care doctors provide, we must provide more suitable care. People get sick the only way they know how.

Frail older adults consume a lot of care. Far better that those of us in the health system treat them as our very best "customers." That would improve care for everyone. No one admitted to hospital benefits from poor sleep, but (mostly) we get away with it in our fitter patients. Not so in the frail, in whom it leads to worse outcomes: longer stays, more confusion, more medications, more falls and a higher death rate.

No one benefits from being immobilized too long. No one benefits from not having medications reviewed, or from poor nutrition, or inadequate pain control, or getting admitted when care at home would be better, or in not clearly discussing goals of care. Just because the health system mostly gets away with it in fitter patients is no reason to forego change.

Changing routines to improve care will benefit everyone. But it won't happen if we see frailty as an acceptable form of ageism. We need to invest in better care and in better understanding how to design, test and implement it.

As important as subspecialties are, by definition, each subspecialty group benefits a small fraction of people. The skills required to provide expert generalism, particularly for frail older adults, have been less celebrated. Compared to disease research, ageing and frailty are barely on the funding radar screen.

In any guise, ageism can be insidious. We don't have to go far to find it. I find it in myself when I'm in a long line. It's not the science of how movement becomes slow that saves me then - it's realizing that slowness is not a moral failing, much less one directed at my busyness.

What we do in our health system now fails older people who might benefit if we provided better care. In that way, it fails us all.

Attitudes must change. Medicine should not be ageist. It shouldn't even be frailest. As a society, we all should take up this marvelous challenge, one that we are privileged to face. We must work to provide better care for frail older adults, especially when they are ill.