There is a distinct difference between mandating that an individual buy health insurance if he can afford it and mandating that employers provide health insurance.   A huge, huge difference, to be more exact!

1. An employer mandate massively drives up the cost of hiring new employees, discouraging new hiring and increasing unemployment.

2.  Forcing employers to pay for health costs increases the costs of running a business, and these increased costs are passed onto consumers in the form of higher prices for goods and services.

3.  An employer mandate does nothing to address the health needs of the unemployed.

4.  The employer-based system insulates consumers from the value of the health care they are paying for, giving them no incentive to economize, thereby driving up the cost of health insurance.

5.   The employer-based system leads to “job lock,” whereby people are afraid to leave their jobs if they fall ill on the job, because switching plans could mean higher premiums or denial of coverage.

In the article that is the source of the info above, The Torturous History Of Conservatives And The Individual Mandate,  the 1989 article by a Heritage Foundation person (Assuring Affordable Health Care For All Americans, Stuart M. Butler, Ph.D.) states:

"This [individual] mandate is based on two important principles.

First, that health care protection is a responsibility of individuals, not businesses."

Second, we will cover all regardless if they have insurance.  "Society does feel a moral obligation to insure that its citizens do not suffer from the unavailability of health care. But on the other hand, each household has the obligation, to the extent it is able, to avoid placing demands on society by protecting itself…"

Later, Stuart said, that the Heritage’s version of the individual mandate contained “three critical features” that distinguish it from Obamacare’s mandate:

(1) it required people to buy catastrophic coverage, rather than more expensive comprehensive coverage;

(2) it was primarily financed “through the carrot of a generous health credit or voucher…rather than by a stick”;

(3) Heritage’s mandate “was actually the loss of certain tax breaks…not a legal requirement.”