HMOs were a minor player 50 years ago. They are a euphemism for the corporate cancer that maximizes profits at the expense of the sick. Even when I started working in Mass 25 years ago, it was one of the few states with HMOs. They have continued to morph and are now ripe for purchase by the more profitable corporations (pharma) CVS buying Aetna is the first shot. Although Aetna is an insurance company, they offered many stripped down 'products' = HMO like plans.