Gist: large-scale governmental changes like revolutions or healthcare reform seem to be highly path-dependent; the post-change outcome is dependent on the pre-change conditions.
There's this theory (probably tied to Edmund Burke) that the French Revolution was highly tumultuous because it tried to totally upend the system of government that the French had in place before—going from the First, Second, and Third Estates, to a National Assembly, a completely revolutionary change. On the other hand, the American Revolution was less of a revolutionary change: they went from a King, House of Lords, and a House of Commons to a President, House, and Senate.
The idea here is that the dramatic change in the French Revolution created a tumultuous environment (that revolutions generally tend to be unsuccessful) because the huge change is too outside the bounds of the status quo. The American Revolution, which created a king-like President that was similarly not elected.
Similarly, Atul Gawande in the New Yorker piece Getting There from Here argues that successful healthcare 'revolutions' are similarly dependent on what came before. The UK was able to develop the National Health Service because they built a temporary healthcare system during WWII that, when the war ended, people wanted to continue relying on. The Swiss healthcare system, originally composed of private insurance companies, was reformed by continuing on what the had before: the government subsidized private insurance companies to make sure that each individual had to pay no more than 10% of their income.
As Matthew Yglesias writes, this suggests that healthcare reform is path-dependent – an argument that, surprisingly, Donald Trump talked about in the GOP debate on August 6. All this to say that path dependency suggests that implementing a totally new single-payer healthcare system in the US and totally ignoring what came before, especially with the entrenched institutions and corporations and the baggage of Medicare, will probably be extremely difficult or impossible. It seems like we have to consider the path that we take to get there.
I can definitely see how that can be true. I think universal healthcare is one of the main things that an advanced nation should provide and the healthcare situation in the United States is truly out of control. But in a country where costs for just Medicare are extreme, I can see how implementing an overhauled single-payer system can lead to disastrous cost overruns in the highly plagued healthcare system present today. A single-payer system would only solve a symptom; before implementing such a system, we may have to consider solving the underlying problems in the healthcare system that seem like they're continuing to metastasize, like extreme pricing for drugs and hospital care in an attempt to cover for nonpayment, but that drive up prices and nonpayment even more.
I'm not sure how far to extrapolate this, but if it is true that large-scale government reform involves a lot of path dependence, we need to build better mental models to consider not only the outcomes that comparable nations have been able to create but the paths that they took to get there. And if we find a general trend, it might be a pointer that this sort of conservatism is actually pragmatic for creating better reform conditions, which is something that the left may want to consider.
Further reading (from the Vox article):