Part of the issue there is group policy. Insurers by the nature of their business prefer blended groups vs individuals, especially when individuals have a choice among insurers.

Or to put it another way, any insurer offering a "better" policy (in terms of more coverage for less money) will attract the highest-consuming patients, individually.

If they sign up groups with less choice, they're more likely to get a balanced cohort of consumers / non-consumers, young / old, etc. etc.