And that's probably why these things are so rare. After all, it would take a helluva lot of drive and energy to bring such a thing to life--probably much more than it would take to start a company in the usual way. If you were capable of building such an organization, why not retain creative control of your ideas and make millions at the same time?
Making millions doesn't have to be a selfish act, by the way. If you want to help people, money affords you the opportunity to do so in any way you please. Horray, effective altruism!
Meanwhile, if you start a software co-op... who exactly are you helping? Software developers, who get a chunk of profits instead of a measly 150K? Software consumers, who're likely business owners? Folks who have money to pay for software?