> socialized healthcare system with the same spending is unlikely to provide any improvements in life expectancy.
That's probably not true, because as the author pointed out, Obesity is considered an "external factor" but many countries with socialized medicine have programs to tackle these issues. Americans lack "preventive maintenance" programs that are a given in Europe. I think we all agree throwing money at the problem will not lead to enhanced outcomes, but to extrapolate that to mean that socialized medicine won't lead to a different outcome is not correct.
A classic example is physical rehab. In the US, getting insurers to pay for physical therapy is difficult and often capped. This in turn reduces long term mobility and leads to issues down the road. In Europe, it's far easier to get physical therapy leading to better long term quality of life.