I think, it’s mainly a matter of the works to which Creative Commons is typically applied, being less suitable for collaboration. You might occasionally see remixes, but that’s mostly it.

In the case of open-source, collaboration is what elevates it, and often makes it better than paid-for software.
You rarely see Creative Commons works that outdo paid-for works in terms of objective quality. Heck, chances are that more collaboration happens in paid-for works, because they can hire an editor, a sound engineer etc…