This feels like the worst possible argument against public corporations. There's a whole sector of the stock market for health care, and you can easily buy funds that only invest in that. What other services to retirees need? You will be able to find listed companies providing all of those services.
There are some technical imperfections in a basket of equities. If your intention is to exactly hedge living costs, then you would also seek to own bonds from those companies, much of the economy is not public, and so on. There are valid points to be found, I don't think these are what you're concerned about.
In the big picture, owning the means of production is the only game that makes sense. What's the alternative? The best store of value is a collection of things that people are paying for, because that's central to the economic definition of value. Otherwise, everything is gold or bitcoin.