I think there are use cases for open source. E.g., you write some throwaway code, and want feedback - the obvious strategy is to publish it open source. It becomes clear that the app you are working on is not a viable business - maybe the code is useful to someone else, and if you were tracking licenses properly it costs nothing to publish it. Some types of software, like compilers, I simply wouldn't trust if they are not open-source.

But it's also true that it is easy to buy into some strange ideas like "sharing is caring" and end up going past reciprocal altruism and into territory where you are working for free.