Republican obstruction and wanton destruction is responsible for the lack of progress. Refusing Medicaid expansions and then overturning the individual mandate is what gutted the plan.
And sure you could jump right into single payer without any incremental change. But you're going to put the 400,000 Americans currently working in the health insurance industry out of work, if you do that. Which is not a small consideration. (That's per a CBO analysis of the feasibility of single payer, which does conclude it would save money, but it will require a massive work transition.)
I'm deeply afraid that this might have turned out differently if she had even something as simple as cannabis in her system.