I think the answer is a "yes, and"

Of course the approach works, we can see it work at various scales. I think what prevents it from working is that it works best when it is the only option. I don't think we could support 5 kaiser permanentes. And that feeds into insurance - there are a lot of insurance plans, and each of them would likely only support their specific kaisers

So ideally there is one insurance, with one provider that has vertical integration everywhere and then indies outside the network you can go out of pocket for, and oops I invented single payer