The Massachussets (read Romney) approach to expanding access to care, which became the blueprint for the Affordable Care Act is far from being an adequate solution to guaranteeing health care for all. Universal (or "single payer", an euphemism created in the US to avoid the "socialized medicine" label) systems are demonstrably more effective and equitative in that regard.
Nevertheless, more access to health care is still better than none, and contrary to the McKeown thesis, it can be shown to have an impact at the population level, apparently:
Mortality Drop Seen to Follow ’06 Health Law.
The skinny, for the lazy: "The death rate in Massachusetts dropped significantly after it adopted mandatory health care coverage in 2006, a study released Monday found, offering evidence that the country’s first experiment with universal coverage — and the model for crucial parts of President Obama’s health care law — has saved lives, health economists say."
Sommers, B. D., Long, S. K., & Baicker, K. (2014). Changes in Mortality After Massachusetts Health Care Reform: A Quasi-experimental Study. Annals of internal medicine, 160(9), 585-593.
From its abstract:
Conclusion: Health reform in Massachusetts was associated with significant reductions in all-cause mortality and deaths from causes amenable to health care.