You seem to not understand the basic principles of insurance.
Large scale insurance, whether it is home, business, auto, etc is about shared risk.
Selling junk policies splits the pool into two parts.
The cheap plans don't cover anything significant and exclude pre-existing conditions. 
They leave people at high risk of financial ruin for their lifetimes.
If people in the junk plan pool are fortunate enough to survive without being canceled 
or cost-limited, they will eventually graduate to a comprehensive plan. But they run the 
risk of being barred from that pool due to pre-existing conditions that went untreated and/or
undiscovered dur to their cheap plans.