I am old enough to remember families (my own included) being destroyed by this same reality pre-ACA. Insurance being tied to your job was a pre-aca reality.

I was born with heart defects, pre-aca it was literally impossible for me to get private, non-corporate coverage, I tried for years.

At least denying coverage for pre-existing conditions means that getting diagnosed between jobs isn't a complete family destroying death sentence like it was for mine.