It would be an interesting experience unless you were dining with someone as portrayed in recent Norwegian Cruise Line tv ads
I don't see it has having a big enough customer base with one party per month and only having 12 for dinner so it really shouldn't upset the restaurant owners since the hosts are pretty much skirting the health dept regulations which brings done overhead quite abit.
The one problem area I see for the host is liability. I'm not thinking of food issues, rather what happens if someone gets hurt or injures on the hosts property? As a non paying, invited guest I would expect my homeowners insurance to cover such a problem. However these people are registered as a business and the people coming to the dinner are paying a fee. Will the homeowners insurance cover an accident of injury??? I don't know but I think the insurance company would try to find everyway possible out of paying and they might succeed. If the insurance company gets off the hook, then the hosts are on the hook personally.