Why Don’t Businesses Just Reimburse Individual Plans?

I know that companies can be penalized for not providing insurance to their employees. I was wondering – why don’t large businesses just give their employees a subsidy so they can go to the Marketplace and buy their insurance — instead of going through all the trouble of selecting and negotiating for plan(s) and having to pay someone to administer the coverage? In other words — if a large business wanted to just, say, give every employee $10,000 per year to buy insurance through the marketplace, would the business still be required to pay a penalty for NOT providing insurance? It seems to me that if there were no penalty for doing something like this, there would be LOTS of large businesses that would be happy to get out of the business of dealing with insurance companies themselves. Thanks!