The only reason big companies offer health insurance is because it limits employees's freedom. It would be easy for the Fortune 100 or 200 in unison agree to eliminate health care and provide a higher salaries. It would make the companies more competitive globally and it would free them from a whole lot of other nonsense, but they don't drop healthcare. The reason they don't droop healthcare is because healthcare and pre-existing conditions limit employee options and it suppresses wages. Also if there was universal healthcare it would be easier to start small companies and attract employees, those small business would be competing for employees against big companies on equal footing.
Healthcare is a racket limiting not just healthcare but freedom.