Yes but the Medicare plans are private insurance, the same insurers for the “commercial market” as you call it. You can’t separate the insurers dropping providers from networks and buying practices/hospitals from Medicare plans to non Medicare plans.

In other words if you aren’t a Medicare patient and are insured by UnitedHealth for example, you will be subject to the same networks of doctors/hospitals as their Medicare plans, so private is driven my the Medicare plans, because Medicare rules are driving the consolidation of the market.

And yes everyone will tell you star ratings are about “outcomes” not price, but if you knew/know anything about the star rating metrics it’s obvious “outcomes” is marketing/PR for cost cutting. Otherwise I’d ask to point out any metrics that increase star ratings that don’t lower costs, whereas it’s easy to point out the metrics that result in better “patient outcomes”/higher star ratings but lower quality of care.