It was a big aspect in 2009/2010 when ACA was being passed.

The reason people want insurance tied to employment is because they benefit from lower premiums because their risk pool experiences less healthcare costs than the general public.

If everyone was dumped into one marketplace and risk pool, then the insurance premiums would have to rise for those working in white collar businesses who had previously been able to enjoy lower premiums since the nature of employment as a requirement precludes many sick people experiencing healthcare costs.

So when people complain that ACA increased their healthcare costs, what they are actually complaining about is having to now share risk pools with sicker people who previously were not getting healthcare period.

The optimal way this would work is if everyone was dumped onto healthcare.gov, and they picked whatever health insurance plan they want, and then naturally the premiums would balance out over time so that the costs are spread amongst the whole population.

Basically, taxpayer funded healthcare, except instead of one managed care organization (the US federal government) you have multiple (United Health, Anthem, Kaiser, CVS, Humana, etc).