-- Absolutely false. Employer-provided insurance was NEVER required. Most employers began offering it in WWII because there were wage controls. The only way employers could attract workers was with benefits. Exempting the benefit from federal income taxes made it even more attractive. But it was NEVER required of employers, it was voluntary. 

And your description of adverse selection is so garbled, that I can't make sense of it.  In the health insurance field, adverse selection manifests itself through healthy people choosing skimpy polices and less healthy people choosing more generous plans. Sorry Larsie.