“not being able to get what one needed”
This is due to premiums being numerically fixed by contract.
It is possible that an insurer might fund profits and administrative costs on a per claim basis and for care by billing insured amounts that vary by month.
The entry month premiums for a person of a certain age might be $800/month. The profit amount for each claim might be 5% of the Medicare allowable amount and the administrative amount for each claim might be $10 plus $1/Medicare eligible line item plus 8% of the Medicare allowable amount. The care and product amounts paid to providers would be as per contract.
In January and February, the premiums would be $800/month. In March, the premium might be $820. In April, the premium might be $787. In May, the premium might be $813. In June, the premium might be $826.
The ‘insurance’ company would simply act as a claim payer.
The financial risk would be borne by the covered persons.
The Medicare allowable amount might be $22,000. The ‘insurance’ company might have contracted to pay $27,000.
There is more than one way to skin a cat!
Problem is too many people with their hand in the cookie jar for anything to be done