Except, before the ACA they could refuse to take you on because of "pre-existing conditions". I know several people who did not switch away from jobs they hated because they risked losing health care. And freelancers, even if they commanded high salaries, also had problems getting reasonable insurance.
I'm up-to-date as of 2011, I'm sure things have (and still are) radically changing - but the health insurance situation in the US was a horrible mess until recently - Everything worked fine until the day it didn't, and then you were possibly shut out of healthcare.
HIPAA in 1996 limited the ability of insurance plans to deny coverage based on pre-existing conditions. As long as you didn't have a gap of more than 63 days with no insurance coverage, they couldn't deny you coverage.
I'm up-to-date as of 2011, I'm sure things have (and still are) radically changing - but the health insurance situation in the US was a horrible mess until recently - Everything worked fine until the day it didn't, and then you were possibly shut out of healthcare.