This whole thing started in 1993.
HillaryCare failed in Washington, but she had buddies in the Northeast States where they completely destroyed the stable medical insurance market, elsewhere, other states, not at all. Hence the huge differences in premium from state to state.
How did they do it?
They killed underwriting and HRPs.
Insurers used to be able to ask questions about health, pre-existing conditions, age etc (underwriting) Those not qualifying for coverage (those with predictable and chronic $100,000 per year claims) would be covered under another program called a High Risk Pool. Typically around 1% of those seeking insurance need to be in the HRP. (hemophiliacs, AIDS patients, the dying)
Remembering, if people already had insurance, they would remain covered as long as they continue paying their premiums. HRPs are only for uninsured people seeking insurance (in any given state) for the first time.
The two public policy entities causing the nightmare are called Guaranteed Issue and Community Rating. The former, as implied, coverage for all comers, and the latter delivering only slightly different premium rates for all age groups. (young people have less money and are generally much healthier)