Well it's both, although the aspect you point out is more important. That would solve a good deal of the most egregious problems. It still wouldn't fix the unexpected $5k hospital bill, but would prevent it from being a $15k fuck-you bill. And with a transparent cost structure, plans would actually be comparable financially, rather than having to guess at their "negotiated" rates or worrying whether they support your current doctors etc.

Politically I wonder what's holding this back, as it seems like it would be more palatable than Medicare for all. Silent hospital lobby? Big insurers that don't actually want to make their market more efficient as they're effectively cost-plus entities?