From a business point of view, successful OSS tends to have the form of companies collaborating to solve a problem they have in common. The equality stand is harmonic with this goal, and completely antagonistic to open core business models.

That's why people can move between companies and continue working on the same code, because it is solving a internal problems on many different companies. And the companies don't block sharing the improvements because the problems the software solves is internal.

Anyway, that business model does not lead to creating companies. It's more prone to creating foundations.