This is because free software is not a business model. Free software is an ethical stance, around which any number of business models may conceivably be constructed.
Very true. And I like encouraging a world where people can make a living serving by their values instead of sacrificing them. I view this topic as "how can I earn money in spite of giving away my software", not "by giving it away".
A startup side project I'm working on is going to do this. We're hoping that by providing something useful to other dev teams, we will raise the profile for the company that's giving the tech away.
If we can earn a good reputation for our tech, we hope that will translate to more signups for the company's product, which uses the tech.
A lot of it is just social pressure and societal norms.
It always looked to me strange that excellent software requiring years of work is made available free, also maintained over years, also with service provided by answering questions in GitHub and forums.