So why don't we see more of that?
Also the law is set up assuming the firm will ultimately be run through a single point of authority, and if you want to run the place as a coop you'll face investor uncertainty and legal difficulties.
Most of all, the US culture doesn't have much in the way of cultural norms for a firm like this. We have centuries of experience working in a hierarchical style workplace, but people don't really have manners for working in an democratic firm, and there would have to be a lot of time and energy spent on cultural factors that a conventional workplace doesn't have to.
Does this make any sense at all?
For a good example, see the evolution of the Kibbutzim system in Israel and what sort of image Israel has today in leftist circles (and the image and reputation Kibbutzim have in Israel's own considerable leftist parties). You will see that leftists cannot deal with individual choices and, also, that allowing individualized choices will destroy any leftist society. Therefore, they cannot be voluntary.