To me, open source isn't a transaction (even one with "nothing owed" as it were), as much as a community. What I get from participating in open source is to be a part of that community. You just don't get the same interactions working on a closed-source, proprietary code, no matter how deep and rigorous your process is. Ironically, I have stronger bonds with some of my collaborators at other companies/institutions than I do in my own, and that's all thanks to open source.
The fact that some of these open source communities happen to have built world-class software that is used by FAANGs and Fortune 500 companies is cool and a testament to the power of this process. But it's also sort of tangential. And I think we're missing something when we reduce open source down to the licenses and code transfer, as if that's all it is.