I remember consulting for a healthcare company in .... 2003. Very short assignment so I never got deep into it, but anyways my consulting company made me read up an in house guide about ALR and MLR (Administrative or Medical Loss Ratios). Obamacare or not, such constraints already exists. Maybe they varied by state, maybe there were other loopholes such as not supporting pre-existing conditions, but IIRC there were restraints on pure profits, so even then the same perverse incentives existed. More revenue you can get more profits.

I am going by very old memory of a few days/weeks of work, but it will be good for a medical system historian to chime in.