I think, that in the knowledge economy the knowledge worker is/must be a co-entrepreneur, regardless of the type of the contract. We do not hire resources, we hire talent and a significant part of it has something to do with proactivity, dedication, loyalty, engagement, etc. So the knowledge-worker is entitled to have a share in the company he helps to create. When it is through some transparent option plan, fine. If not, you get just a normal organization, where most of the people are actively disengaged, where you need for every 3-5 developers a "coach", a "trainer", a "manager", a "supervisor", ... and where the product is boring, services are poor, and innovation only possible through acquisition. In my opinion, this vegetative attitude is socialism (as I remember it from my childhood).

If Mailchimp promised that their culture will be around values, and people were invited to participate in these bigger things, the promise should be kept. The situation may change. When "owners" decided to walk away, then the people should get a fair stake. 300M out of 10B doesn't seem to be very fair, or? I am sure people asked about their stake upfront. And I also think people went far beyond the traditional 9-5 transaction setup.

PS: I see Elaine Sterberg's statement as outdated. A knowledge-based company is very different than the one created at the beginning of the industrial era. Profit-making is the engine, an important indicator of the health of the business. But making money as an ultimate goal for a single stakeholder is weird in the 21st century.