Because the "open source" movement has been co-oped by corporations which promote for precisely this reason.
Actually contributing to a common good is done by building Free and Copyleft software, not "open source" which is term that offers no legal protections and the things you're talking about.
Actually contributing to a common good is done by building Free and Copyleft software, not "open source" which is term that offers no legal protections and the things you're talking about.
https://en.wikipedia.org/wiki/Copyleft