Earlier quoted context omitted.
The insurer is a business, its ultimate priority is the make money. Same as the hospital, the drug producer, etc. I am sure they all want to prioritize client care but that have to ration it by cost at some level.
Insurance firms have the unique benefit of being able to offload their costs to their customer base in the form of premiums. That and excess would be the appropriate level to ration in the cost. Is that not verbatim how insurance works?
Then an insurer can go about negotiating the prices of treatment with health care providers to determine payouts.