Yeah, that's fair. Maybe I should rephrase to say it's a point. I could see someone arguing that forking is just a component of the deeper philosophical attitude about how people can use and distribute and modify code in general.

Forking is the/a point in the sense that I can't think of a version of Open Source that is still Open Source but that doesn't allow forking -- that allowing for forking is a deliberate choice, not an accidental one.